I have been using one of these kits for a couple of months now (direct from China). It's worked fine so far. On take-off, it can be a bit jerky if you try to open the throttle slowly; if you throttle up quicker the clutch engages sooner & therefore smoother. I think it just needs to bed-in a bit because it's a little better now than when it was new. It's nice to be able to stop without worrying about pulling in the clutch as well as rear brake. Also, travel quite slowly without all the pedalling to get going again. The biggest thing I've noticed, is my engine runs a lot quieter & smoother!! I can only assume that the clutch is acting like a flywheel as it's quite heavy. As for the pullstart, I love it! I start it & let the engine warm up while I put my gear on; then it's ready for some right hand action!!
I'm not sure why you have to cut the 3 clutch pins flush for; it's probably due to them rubbing on the new clutch cover. I had extra gaskets supplied with mine, so I put a couple extra behind the cover to prevent that happening. I didn't have any instructions at all, which didn't help!!
Overall very pleased with it, if i get problems I'll post it ASAP.