I've got the 3441B, I got it as it was the lightest / smallest (collapsed) that I could find. It came in 3 days !
The twist locks are the rubber ring type, and probably not as convenient as levers, but levers always stick out and add weight so it's a toss up.
This review (of the 3402)
http://forums.dpreview.com/forums/read.asp?forum=1019&message=16650287
mentions a technique for opening and closing, I read it before I got mine and it didn't make any sense, but having got my 'pod, it now makes perfect sense.
I already had an old Cullman tripod, but that's so heavy I very rarely use it, whereas this one I can stick in my luggage with no problem, and although it might not be the sturdiest 'pod in the world, its certainly better than not taking one at all.
I know of one guy who fitted the short centre column and removed the ball head to save even more weight, - seemed a bit hair shirt to me.
I'm very pleased with mine taking into account it's a compromise. Ideally you want the heaviest tripod available, but then you need a young Amazon to carry it, I didn't have one of those so I went for a 3441
.