I just got the Rekluse z-start Pro installed on my bike and I picked it up late yesterday to ride home (I live about 4 miles from my dealer).
Riding away from the dealer I stalled the bike. I put it in gear, revved it a little and when it started to move I reflexively backed off the throttle and the bike died. Now the reason it died was the bike was cold and I have the idle set very low so I can putt putt along slowly on technical trails. The dealer sets up Rekluse clutches such that they engage almost immediately, and this is what I indeed wanted - I knew it up front. I am just saying this because it caught me by surprise and it is not an issue. Once I get used to it this won't happen, especially when the bike is warmed up - I notice it only takes a few minutes for the clutch to engage a little differently once the bike is warmed up; it is not so abrupt, and the bike hasn't stalled on me since.
It will take some getting used to. I didn't get the bike until late yesterday so all I had time for was to try it out in my yard and my dead end street. I like it, but it will take some getting used to - especially at slow speeds. One of the things I noticed right off was that if I let the bike idle when at a stop on an incline, it would of course roll backwards when the clutch disengages - so either keep moving forward, be prepared to use the brake, or (least desirable) use the throttle to hold your position - I would want to do the last for very long as you are essentially slipping the clutch.
Also, now, the clutch lever seems to be mostly useless (at least to me), so I am thinking about whether to get the LHRB - I think it will be helpful.
Other than that, I didn't notice much difference while riding at speed - it acts mostly like the stock clutch. I purposely shifted up and lugged the bike to see how it handled a load in a gear too high. The bike would lug just a little, but when it reached a point where the bike might start to lurch or buck under load, the clutch would 'slip' and let the engine rev a bit higher and then the bike would move faster and the problem would be solved. The slipping is not a problem, from what I understand this is the design to prevent stalling. I wouldn't be intentionally riding this way normally, but I wanted to know what would happen if/when I mistakenly try to climb something in the wrong gear - and it did what I expected.
Just with playing around with some moderate inclines in my yard, I think I am going to like it. I will find out for sure today when I take it out on the trails.
I do think I am still going to want to get much lower gearing. For one thing I would prefer to be riding along well above idle, instead of at idle as I do now on some really tight stuff. For another, I think this will help with downhills as the clutch will be disengaging at a lower speed so I will still have some engine braking at slow speeds.