I like big packs. They make packing way easier and give me the margin of error to add an unexpected item if needed (e.g. bear canister, large glass fish float found on the beach, 5 gallon bucket, firewood, an injured or sick person's gear, etc.

In making my own packs I have found that a large pack can be made that weighs very little more than a small pack. With a frame pack, for example, the frame, waist belt and shoulder straps are about the same for either pack. The volume of a bag can be doubled by only using about 50% more fabric and nylon fabric is very light. So the difference in weight between a large pack and small pack can be as little as an ounce or two.

My very large myog external frame pack, for example, weighs well under 1 pound.