I'm looking at haibikes. The lower models seem to have the yamaha pw. As you go up the range a little it switches to the Bosch cx. I'm trying to get a test ride of both, but for any of you that have ridden both what are the pros and cons of each in your opinion and what did you prefer? Thanks
Which you prefer is probably going to be down to preference. The Yamaha seems to have a smoother, more controlled delivery. The Bosch maybe a bit harsher, more 'in your face'. My wife likes and prefers the Yamaha approach, I don't mind the more aggressive bosch.
A big one for me personally is cadence. If you don't pedal above say 75 rpm, the yamaha is fine. However check out the power curves of the PW motor, you'll find that power starts to fall off above 80rpm, and by say 100rpm, there is virtually no assist. I often sit and spin at 85rpm and above for extended periods when road riding, so a PW motor wouldn't be my own personal choice for ME for a commuter bike. For other people, its a non issue.
Bosch CX has a high cadence support. (Note - Yamaha PWX also has increased cadence).
You can get cheap(er) 3rd party batteries for Yamaha. You can't as yet for bosch!
The yamaha charger plug is a poor design and you have to be careful you don't break it. And a new charger is slightly more than the already pretty expensive bosch ones.
It really is six of one and half a dozen of the other. If max cadence isn't going to factor into it, then things like the fit, style and cost of the bike as a whole are probably going to be more of the deciding factors.