I always put LowRider racks on first, then only add rear racks if I need more capacity or the ability to carry odd objects. Routine compact weight always goes in front. Reasons? Handling. Weight, ever 30+ pounds in LowRider panniers have surprising little effect on handling and even less on the handling of the bike when climbing out of the saddle. The effect on steering actually turns out to be a plus if you have to ride in slippery conditions. (I used to carry more books than I needed when I commuted into campus on bad Ann Arbor winter days just for that benefit. I could ride up the short un-plowed hill from my apartment with heavy panniers up front, throw my weight back over the rear tire for traction and have enough steerage to pull it off. If I was traveling light, I had to walk. I wouldn't be able to pull off both steering and traction, (Riding a fix gear. Sitting wasn't an option.)

The drawback to loaded LowRider panniers is that your front wheel will take much harder hits on potholes, etc. I simply ride bigger tires and stick to strong rims. In Portland, I ride 28c Paselas (Edit: or larger; 32 or 35 on my "truck") on either Mavic Open Sports or Velocity Aeros. (The Aeros are a lot stronger.)

When I go to the farmers market on my "truck" (racks front and rear, all four panniers small front Ortliebs) I load the right front with apples and pears, root and other heavy vegetables in the left front, leafy greens in the right rear and clothes in the left rear. I haven't toured for years but I used to put cook stuff, cans and metal items in the front panniers and sometimes even my tent. Clothes, sleeping bag and bulk items in the rear panniers and strapped to the rack.

There is one handling issue using LowRiders. Pannier clearance. I've dragged my Ortliebs a few times. (They are very durable. They survive road abrasion better than either me or often the bike. I've done one repair on my 19 year old first pair - stabbed it with a very sharp kitchen knife. A standard raft repair and it is as good as new. Still holds water. Call any rafting company. They will tell you where to get the materials and walk you through the repair.) For slightly better road clearance, consider the Jannd racks. They sit higher and are much stiffer and longer lasting. Also considerably more pain to get the front wheel with quick release through. I use Blackburns on a couple of bikes and the Jannd on the "truck". For the truck, I replaced the hollow QR axle with a bolted one to get the width down. (Phil Wood - uses an Allen wrench.) I call all those racks LowRider in appreciation to Blackburn who created the first just like I call those ubiquitous adjustable wrenches crescent wrenches in appreciation of the contribution by Crescent Tools to a better world. (And yes, crescent wrenches should not always be used. Specific tools are better. But the specific tool that is at home or doesn't fit is useless.)

Ben