things to look at when comparing swags.
Poly cotton mix canvas is cheaper than pure cotton canvas but not as breathable or long lasting.
When checking mattress support, do not pinch but put hand under and hand above mattress and then push flat of hands together to get better indication of support.
Store should always let you climb inside (shoes off), lie on your side and see if hip and shoulder is supported off the floor.
The density of the foam gives the support, some swags have two layers of foam, higher density foam under the trunk, less,dense foam under the legs. Helps to minimise size of swag roll.
Some people like eggshell foam but it increases size of swag role.
Fibreglass poles stronger and more durable than aluminium poles
Check zip quality, YKK zips good reputation and self repairing.
Check stitching, better swags have really close stitching and double stitching.
Most good swags do not need wetting and drying to make waterproof, that's something from years ago.
Occassionally a swag may weep through needle hole in stitching, once it dries it should seal up and remain waterproof.
If camping frequently on very wet ground, some brands have a poly base. Good on wet ground but watch condensation and mould under mattress.
Hope this helps.
By the way I retailed multiple swag models and brands for 20plus years.