The Stax arrived yesterday, and we took it for its first rides today after assembling. It's such a beautifully realized bike. Easy to pedal with no power assist, and then the levels of assist are nicely tempered. The kids and I find that level 1 is going to be entirely adequate for regular city driving to aid starts and accelerating. We tried it on a few hills, and it's definitely worth incrementing the assist (which goes up to 5), on inclines, although it's just as easy to leave it in 1 all the time and just supplement with the throttle. We got all the accessories that come included with the Stax Pro (fenders, rack, throttle, stem lock), but stuck with the Stax since we thought front shocks included in the Pro version were unnecessary. (We test drove a Pro version).
The bike handles really nicely. It feels stable and balanced; a much more fully conceived riding experience than a lot of other ebikes we tried.
We settled on this model is both because it looks sharp and also it doesn't really look or feel like an ebike. Who knows whether that will make it less of a theft target.
A couple of considerations: the front headlight is built right into the frame -- another real plus -- but the tail light is just a simple little add-on that sits underneath the seat. We tested the ST50, and I really liked the fact they built the tail lights into the seat stays (and that they lit up when braking). We debated a lot about the Stax versus the 50. If we were going to be doing more stuff outside the city, the ST50 (or D50) would have been a logical choice.
There were a few glitches in ordering (both shipping and a part not included) but the support has been very responsive.
Because the stem is big to hold the battery, and the frame is definitely larger than a standard bike, the Mini-7 Kryptonite lock I ordered to go with it is probably not the best option. A little too small and not gonna be easy to mount I think.
Otherwise, the Stax feels like a really great decision.