Yes. We have a carb working on the 610. I thought it worked really nice. The bike owner was on the fence and might put the FCR back on. I think it just needs a slight tweak and it ran great for my test ride. But here is the deal. The Lectron is a VERY simple and EZ to use carb. It is a "performance" carb and not really intended for a bike someone wants to walk out and hit the starter button and let it idle for 5 minutes before taking off nor sitting in rush hour traffic. Why? Well the metering rod carbs are super sensitive to draw. As such the very small metering opening on the rod (remember no idle circuit, no plot jet, etc) controls the idle. We have updated the carb with a air bleed circuit making fine adjustments of the low end EZer. In our 4 stroke testing and also mentioned in this thread there is somewhat of a puff of black smoke (rich) right off idle when snapping the throttle hard in neutral. There is also a good but not 100% steady idle with these carbs. I just want to be 100% up front with these facts.
That said actually riding the 610 test bike it was very snappy, pulled great and ran hard. And this was with little to no adjustments or time to sort some things out. IMHO it ran great. You are removing a super complicated multi circuit carb with a accelerator pump and million other circuits and putting on a single circuit and insanely simple carb in its place. Surprisingly it still has all the snap and power of the FCR regardless. So basically what you are getting is a very good carb that is super simple, EZ to dial on the trail, nearly impervious to water contamination and runs great but are trading away some idle steadiness and might have a slight bit of black smoke once in a while when grabbing big handfulls of throttle. If you have a well sorted FCR your not going to gain a ton of running performance IMHO. Maybe better MPG but that has yet to be verified. Really the big advantage over the FCR is the simplicity of the carb and the ability to adjust it externally and very easily. The Lectron is also very altitude compensating. If those attributes are of interest to you the Lectron might be the ticket.
For any other bike without a FCR I think these Lectron will be a huge advantage. Older Delorto 570/510/610's would run much better with the Lectron and run harder to for example.
Just trying to lay it out 100% as i see it. Make up your mind from there if this is the right carb for you or not. Feel free to ask more questions and I'll do my best to give a honest answer given my limited 4 stroke use of these carbs.
More FCR / Lectron on a 610 info here...
http://www.cafehusky.com/threads/610-lectron-installed-and-tested.34614/
Very EZ to get to the air screw, idle and choke as configured even with the big IMS tank. The rod was EZ to as you can just rotate the carb and pull the slide out without removing the carb.