I have only seen a handful of psychill live acts, mostly Ultimae artists, but a couple of others too. If I had to choose a couple of them as the ones I enjoyed the most, I would go for H.U.V.A. Network and possibly Miktek. They were both very deep and blissful. I've seen a few DJ sets, most notably two Posford downtempo sets but that's another story - they don't count as live acts. On a final note, I was at the Twisted party the Hallucinogen in Dub live album was recorded, but I find the studio album noticeably better. Younger Brother were quite enjoyable live too, in a similar line-up to Shpongle, as was Ott (on his own), but again nothing to go crazy about IMO.
What about you? Any live downtempo experiences you would like to share? Possible disappointments can be discussed too.