never used a Khaler but would like to - Slayer use 'em and always get SERIOUSLY chunky tones.
I think that's despite, rather than because of, the Kahlers. I've got a couple of 80s Kahlers, haven't used them for years, but I always felt they robbed a bit of sustain. Of course, the same's true of all trem systems IMO.
The feel is excellent though,
much better than a Floyd (although I hate Floyds, so don't take that as gospel

). And the locking feature will make them easier to set up.
You do need strings with reinforcement at the ball-ends though - ordinary strings don't last long. Kahler made their own strings at one point, which were rubbish - they broke before the guitar was even in tune. The best ones are Ernie Ball RPS, but I don't think they do 7-string RPS sets.