Originally Posted by
CFXMarauder
Id do what I currently do now.. Bring in a weeks worth of clothes to work by car on my day off, commute wearing shorts, gloves, clipless shoes and a DriFit shirt..In the 1 year, 9 days 4,277.5 miles ive owned my Allez sport ive never found a problem with pinch flats or warped rims and I run between 183-195lbs..If you really want bags shell handle them just fine

. Never tried fenders, I cant stomach the looks of them but if you have a rack it keeps you from getting a mud stripe up your back..Ive had no problems with the seals and bearings from rain either.. Id rather commute fast and lite so things have changed a bit from that pic..
Where does the OP live?
Try going no fenders in a 35F hard rain for a 20+ mile commute. If that weather is a possibility, fenders are pretty much a necessity. And if the OP still wants to ride a "fast" bike, he's going to need two. Or more.
And no backpack in the world can avoid creating overheating issues when temperatures reach 90-100F or maybe even hotter with any humidity. When temps like that make it necessary for you to be able to dump heat, covering up a large surface that would otherwise be wide open to ventilation is not a good idea.