I'm looking for an uber tough really large dry sack to line my 35L pack. Would this product fit the bill? Any other recommendations? I am not super concerned about it being absolutely waterproof but would find that a nice perk. Is this product super durable even with the sharp corners of prepacked food?

You could always go the cheaper route and use extra large heavy-duty garbage bags to line your pack with. It gets the job done and is lighter than any of the other bags listed. Some even have a "stretch factor" included so that they won't puncture right away if they get rubbed the wrong way on the corners of prepacked foods, etc.

As Sandy says, this is fairly tough for most gear, but "Uber tough" it's not. You'll definitely pick up some weight in the process, but the best thing for what you're looking for is going to be the SealLine Black Canyon Dry Bag (item# CAS 0573)...now that's uber tough with an attitude. A couple other serious contenders are- SealLine Storm (item# CAS 0607) Outdoor Research Durable (item# ODR 0470)

This would work. It should be tough enough for most gear (open knives and pointy things excluded). The other one to consider is the Pacific Outdoor (http://www.backcountry.com/pacific-outdoor-equipment-dry-cylinder-dry-bag-915-2136cu-in). It is equally tough, but has a clear window so that you can see what's in the bag and where in the bag it is. A huge help!!!