In reply to UKC/UKH Gear:
It seems the only part of a sleeping system I'm missing from S2S is a mat, the other things I've got are all comfortable, light, well designed and look like they'll last me years to come.
I've also got a 2 person hammock, which although likely isn't going to be the first choice for most in terms of a sleeping system, (myself included) it packs down to a small water bottle, has ample room for one person and is great for hanging out on nice sunny days.