I have one on my commuter bike and my reasons for going with the tsdz2 nearly mirror yours.

I don't think you lost anything by going with 500W instead of 750W. My observation is that, in its highest setting, it seems to add about 150% of what I put in. By that, without it, on a commute, I am generally between 10 & 15 mph. With it, I am between 15 & 20 mph.

The big difference for me is that in winds that would push me down to, or below 10 mph, with the motor I am still around 15 mph. However, it does not get even near adding 750W.

In all I am happy with it for the purpose I use it for, making my commute a bit more enjoyable; yet I still get my heart rate up and I can feel my legs, I am still pushing. As was noted by the OP, I still need to use the gears.


I wanted to add, a while ago I mentioned some error codes. Then it stopped working when my daughter was using it. The problem turned out to be a poor crimp on a power-pole. Once I fixed that I have had no error codes.