A big thank you to all of those who posted in this tread.
I installed a tsdz2 48V 500W on a raleigh bike (build thread hopefully following) and I must say it works better than expected. Torque sensing is just the way to go if you ask me, since it starts the motor almost immediately after you start pedaling. Every other PAS system requires some initial pedaling, which can be very hard on the knees (at least for me - that's why I build an ebike in the first place).
The second best thing is probably the Xh 18 display. A grip shift switch just feels so much more natural than the usual button pushing, especially when combined with a mechanical grip shifter on the right side. I miss a few options in the menu, but they don't make up for the smoothness of grip-shifting...
The power delivered by the motor is ok for medium climbs. I don't expected to last in the alps though, especially when hauling a 50Kg trailer.
Now the negative part: noise. I read about it here, and if it is really random, I was probably unlucky. My unit makes a strong noise under load, somewhere between a rock grinder and a small lawn mower. Since I got it directly from china (no reliable importer where I live), return is no option, so if you guys figured out where the problem comes from, I'd be glad to try it. On the commuting road when riding next to cars, it certainly does not matter - yet the noise really tends to kills the quiet experience of forest tours. On the plus side: no accident with pedestrians so far!