I for one have never thought about the size of the "bed" but rather what i was sharing it with,; I suppose that is a bit of a commentary on my musical taste and such. Indeed one does need a left and right handed model to secure the _______...fill in your own notion. I have operated thermarests for many many years and have yet to burst one yet, slow or otherwise...but I think that is more of an issue of overall mass to be sure! DB has a wise point about the draft issue...cant say I have ever noticed it before maybe that is about the focus at the time ;D BA sorts out the sliding mat issue that is all to common of a problem, before that I stitched up my own webbing system that served the purpose and a few others. Have fun and live long & prosper. Its camping right!