I put one n my spare Swift, commuted with it for quite some time, put many miles on it. Like others, I also found mine to be the cause of knee death, and set about modding it. I opened it around 5 times to get it perfect. It shifts at 27km/h.

The upshift is seamless, while the downshift requires you to ease off the pedals momentarily. That is a very good thing as you don't want the resistance to suddenly drop as you are standing on the pedals cranking up some hill.

The only times I found the upshift slightly unwelcome was when I was sprinting away from the lights and would have liked it to stay in low gear slightly longer.

I have the backpedal brake version. I didn't think it to be draggy, and I am obsessive about stuff like that.