Good bits first:
The motor performs really nicely! The motor's power and top speed at 48V is exactly what I wanted. It pulls enough that I don't have to work very hard up the hills, though I do have to work (which is what I wanted—assist, not pedal-less climbing). The top speed is good. I don't have a speedo, so I can't tell you exactly how fast, but Strava reports my top speed at 28.2 mph. I'm positive the bike can go a bit faster, but the twitchy steering had me a little nervous so I was taking it easy. At top speed I was still able to contribute pedal input without just ghost pedaling, which was one of my biggest complaints with the fast Q100.
The bad bits:
There's only two, the motor is noisy—even with the FOC Phaserunner. I don't even want to imagine what this thing sounds like with a square-wave controller. My BBSHD is the quietest, and on the Phaserunner I would say that the Q100 was only slightly louder. The YTW-06 is definitely a bit louder than both. It's not dramatically louder in terms of decibels, but the tone of the sound is more like an electric motor sound rather than the deeper hum of the Q100. My other dislike is the clutch; it's noisy too. I didn't feel any drag when coasting with no throttle or pedaling, but I could hear the clutch. It is just about drowned out by my loud White Ind. freewheel, but if I'm pedaling with no motor, it almost sounds like my brakes are rubbing or something (they're not, I checked twice).
I have read that both of these things get better as the motor breaks in and things seat with each other better. I will be sure to update either here or in the motor thread if and when that happens.
First impression conclusion:
With only the one 2-mile test ride, I can't make any proclamations about the motor yet. The weather this week is going to be awesome here in Atlanta, so I'm going to be getting 50-60 miles on it at least. So I will post again next week with my real ride impressions of the motor.
My first impression is that the smaller size and lighter weight make this a very nice mini hub motor. It is definitely without a doubt worth the $75 + shipping. If you're already running a Q100, I'm not yet certain it's worth swapping out just for the size weight differences. if you don't yet own a Q100 or the one you have has died, this motor should be at the top of your list when looking for a replacement/alternative. The motor seems to pull just about as hard as the high-speed Q100 did—which is pretty crazy for such a little motor. I think I can tweak settings in the Phaserunner to get this running even better. I was a bit conservative on my initial settings, and I didn't go near any of the advanced settings other than adjusting the throttle input levels.