i have no expireience with the above, however i have recently purchased one from nunatak and have found it to be great! still have not gotten into the really cold nights with it, but cold enough that i would normally consider putting thermals on and i was still fine. the weight is HEAPS less that the raysway one, his claims to be 1.5lb (680g) where mine is only 18oz (510g). the price is the only thing that gets it really, as mine was a shade under $500 delivered. however, mine was also custom made and has some of the best workmanship i have seen on it and it was delivered to my door in a post satchel ready for me to sleep in imediately.
As far as I can see the only bad thing people have had to say is it does not pack down really small.
didnt look to see how small it packs down, but mine is in an XS size eVent compression sack from S2S and it compresses as small as the sack will allow it, and i think it could go smaller if it was in a smaller sack... about the size of softball.