I have a plain old regular Timbuk2 bag (which is probably closest to the Covert), but in a large. Its a great bag and held up really well to some serious punishment. Not the best bag in the world (strap could be better), but certainly not the worst ... and for the price, it is hard to beat. My concern with the Commute is the zipper on the laptop pocket, which probably will not be waterproof in a heavy downpour. The main compartment of either bag will be essentially waterproof (assuming you don't throw it in a lake). My laptop has stayed bone-dry in the main compartment of my bag in some serious storms.