Wow, I might have to pick up one of those. Also looking at the REI Flash18. My packing list for my next trip is trimmed down to what will easily fit in two smallish panniers with room to spare since my tent, sleeping bag, sleeping pad, and pillow (actually a down vest in a tiny pillow case) will be on top of the rear rack. One of these would be great to hold the stuff on the rear rack and it would be handy for side hikes and shopping runs as well.

Does anyone know how water resistant either of these packs are? I am guessing I'd need to pack stuff in plastic inside the pack in wet weather. Is that the case?