Sorry for the long response Fairmont, but it took me a long time to research all of this stuff over the last few days online and on the phone for myself and I think my research might help you and others as well. Also, my needs have changed over the last month so my current system is no longer plausible. I am hoping that my research will help others and I have tried to put all of the information together...hence the long response.
I have been using a trunk bag and rack from Topeak for the last year and it has provided me an excellent way to transport what I need for work up until now. My commute is about 12 miles each way. I also used a Hydration/summit pack from "North Face" that included a pack cover for rainy days and also had the ability to add up to a 3 liter bladder for really long rides or multiple uses. Below see the +'s and -'s of this set up.
Topeak trunk rack system:
+'s:
1. Topeak's system (MTX/Quick Track) uses a slide and snap system that allows the rider to easily take the bag on and off and secure it nice and tight. The old ones like I have worked on all rack types as they also had velcro to attach to the rack like all other manufacturers trunk bags work. They do not now, but the bags themselves are better built and streamlined to fit better under the seat now.
2. The system works very well together and is relatively cheap compared to other systems.
3. It is easy to mount whether you have the mounting braze-ons for them on your bike or if you need P-clips to attach to your seat stays. The system has been rather sturdy for me loaded up w/ about 20-30lbs.
-'s:
1. Their system for the trunk bag now only works with their system.
2. If you want it to be waterproof, you will need to either by a rain cover or purchase their dry bag series where the fabric of the bag is already waterproof.
3. If you need to bring a lot of stuff or if the items you carry do not fit you are limited by how much weight you will want to put on your back and/or the trunk bag. As stated below from other responses the more weight you put in either spot the more issues you will have with back/neck/ or joint pain on your body or issues you will have with bike handling by putting too much weight too high on your bike.
This is why I am now considering going with panniers and I have spent about 6 hours trying to make sure I make the right decision. Based upon phone calls with various manufacturers and researching this forum and others (great resources and many thanks to all of the posts and conversations I have had with Ortlieb and Arkel) I have the following points to make below:
Topeak:
I originally was going to purchase the Pannier Drybag as it was an excellent price for two bags compared to only 1 bag listed below from Arkel/Ortlieb. They would make an excellent pannier, but not the greatest briefcase or carry bag once off of the bike. Lastly upon measuring the gear I was going to be taking to work each day, it was going to be too tight of a squeeze (see measurement information listed below at the end).
Arkel:
As stated before by Macteacher, the Arkel commuter is an excellent choice if you need to carry a laptop.
http://www.arkel-od.com/panniers/com...asp?fl=1&site= . It carries the load more vertically so if you need more heel clearance based upon foot size or length of chain stays it is an excellent choice. Arkel also has a very unique laptop attachment (suspends the device above the bottom of the pack to protect if from bouncing during the commute into the bottom of your bags) system that comes standard with the "commuter" and with the "briefcase"
http://www.arkel-od.com/panniers/bri...asp?fl=1&site= . I only have two concerns with the breifcase. First, will I encounter heel strike as described in other threads and warned about by the Arkel rep? Secondly, how water-tight is the case? I asked in another thread how waterproof the Arkel bags were and Landstander assured me with the rain cover that he had never had an issue with water coming into the bag. I also called Arkel themselves and spoke to an excellent customer service person who walked me through the system and also assured me about the waterproofness of the system. The side of the bag that is next to the wheel where the raincover does not reach will get wet on the outside, but it will not penetrate the inside based upon fabric material and the plastic insert. You could always use tent seam sealer or rainfly/tub sealer to double protect if you were concerned. The issue with heel-strike is still up for grabs as I will not be sure until I mount the system using my current Topeak rack system. I currently ride a Surly Crosscheck (size 52) and have a 44-45 size foot. Currently I use "P" clips supplied to me by my LBS. The system works well and supports my current load. See the next link
http://www.thetouringstore.com/TUBUS...ONS%20PAGE.htm . It provides an excellent place to buy rack accessories if you need a nicer looking solution to P-clip solution (also lets you remove the rack w/out taking the clip off), provides a solution for a quick release set-up which will further extend your rack backwards for heel clearance, provides sales for Tubus racks which some models have 2 areas to mount your panniers to move them farther backwards...LOCC is a good example, and lastly if you are interested in Ortlieb they are a great and cheap supplier that offers free shipping !
Ortlieb:
Another option is the Ortlieb Office bag large
http://www.ortliebusa.com/cartgenie/...p?pid=79&cid=2 . It has two advantages over the Arkel. First, it comes waterproof, so no need for an additional rain cover. Secondly, it mounts slightly tipped forward allowing for more heel clearance so again if you have big feet/short stays this system may work better. My only concern for this bag is its size based upon what I need to carry with me to work now.
Both Arkel and Ortlieb bags:
Both bags appear to be excellent choices from either company. They have easy systems to just pop the bags off, have shoulder straps, and look rather nice off/on the bike. For me, if I knew everything I wanted to take to work would fit in the Ortlieb I would probably choose that one. However, I think the size of the Arkel is going to work better for my case. I have to bring at various times to work a large planner, organization folder, laptop, and various 3-ring binders. Remember all three of these bags (Arkel Commuter, Arkel Briefcase, and Ortlieb Office bag) come as individual bags and not a set. This allows you to pick and choose what you want on each side and you can mix/match between panniers, grocery bag holders, etc... to make the best set. Also remember that the measurements on their websites are from the outside and not inside so it is important to measure the items you are carrying to ensure they will fit (give yourself an extra 1" or so).
Summary:
So it appears the Arkel Briefcase will be the winner along with the extra raincover needed to keep my stuff 100% dry. I think I will add the "Utility Basket" from Arkel as well to carry groceries, clothes, misc...etc. I hope my Topeak rack works with the new bag as it will allow me to continue to use my trunk bag set-up if I need additional space. If I have to go the "Tubus" rack route to give myself additional clearance it will be a beautiful set-up, but cost a mint. I think I will try the quick release system first (if I only need 1-2") as it will give me a cheaper solution than a whole new rack and I will also add the "Stay Mount Clamps" as they give a cleaner look and ability to remove the rack if I just want to go for a long road ride. I hope this helps everyone out. Now all I have to do is scratch up the necessary coin to pay for this all. Anyone need a Campy Record 9 cassette for a good price?
Cheers,
Erik