We are using the less expensive Hack Sack by Leisure Industries.
These are not as thick and puffy as the Travasaks. The colors and the sizes vary between the two brands.
The reason we chose Hacksack was for size. We bought it for the 3/4 corner bed in the 25' side sleeper. Even the full size was too large for the space and we had to fold the side over, but the Travasacks were much larger. Between the two the Travasacks are probably nicer in quality, but if there is a size or if the color varies you might consider those as well.
The sleep system is quite handy. It is much easier to smooth the covers than to tuck in. The sheets stay attached and velcro in and out. Colors and flannels are also available. There is a summer and winter side. I place our AS bedspread over it though.
We will probably get a comforter and skip the top sheet when I find ones I like for the new queen bed. I just don't have any sheets for it and I still had the hacksack.
If you like sleeping in a sleeping bag you will love it. We are leaving the zippers open to slide out more easily. But when it's cold zipping up really keeps the heat in and the drafts out.