Just ordered the Timbuk2 Raider and currently use the Osprey Radial 26.

I leave shoes at work and they have towels in the gym, but between laptop/clothes/pump/tubes/phones/wallet/deodorant, I've found the pack getting pretty heavy and it can take the fun out of the ride. The Osprey packs can be heavy and although the Raider is only about 1.5 pounds lighter, I suspect it will be a notable difference.

Not sure how long your commute is, mines about 12 miles each way, but weight might be something to take into account.