I've been using Kahuna since it first went to beta, and despite the occasional hiccups, I've never regretted it. (Certainly never felt like opting out!)
It's really good to see an update video - even if it is a month old! It's ironic that, as this video goes out on Channel 9, Windows Live Mail (beta) has spent the last six hours or so being a complete arse! This is after spending week with the welcome greeting
telling us that they've 'hit a few bumps' with their latest build! lol!
They're probably rolling-out some updates or some-such-magic as I type. In any case, I'm loving it.