This has been helpful. Still leaning toward a waterproof compression sack but Mat re-interated my chief concern about repeatedly compacting the bag. It has the ring of truth.

On the other hand, it is quite likely this has already been tested numerous times over and I suspect the loft impact is negligible,(or the results would be made known) especially when you consider the average tripper may only spend a few weeks a year using it.

Probably what I will do is snug the straps up but only in moderation. In any event I am so looking forward to one tidy little bundle of mat, bag, pillow and sleeping clothes. I have one of the therm-a-rest pillows and by golly I wouldn't leave home without it. (Aye Matey, gettin soft in my old age)