- Familiarity: I've used it several times
This is a fairly good pad. Unless you have plenty of time for the self-inflating feature to kick in, get ready to inflate it yourself. That said, that's a minor nuance, and honestly, to be expected. The valve is awkward to inflate and every time I do I wish Therm-a-rest had designed a better valve.
If in doubt, get it. Packs next to nothing, weights next to nothing and you'll get a decent sleep with it.
Oh, and if size in your backpack is a concern, get a small, you don't really need that much padding on your legs, and the small hits all the important spots you do need a pad for.