Super pleased with both. It's about the most powerful motor out there with the best torque sensor. The level one pedal assist is my favorite in the industry. You genuinely won't feel it helping you, so you'll feel like superman. It also runs really quite, which I love.
I'm currently riding a Surly Karate Monkey Bionx setup. It's my sixth e-bike in two years (not too difficult when you have a shop and don't have a car). Admittedly after doing this build, I'm looking at a titanium build for myself. I'd like to be under 40 lbs., but that's a pipe dream right now. BTW Bionx advises against carbon frames so ti is the way to go.
The coolest thing is I feel like it's one of the best ways to future-proof yourself. Once you have the bike that you really like, you can save money on getting the best. Just upgrade kits down the line and don't worry about the bike. Bionx is stellar and backwards compatible! If you have an 48v s series you can upgrade to a d-series motor right now and save $1300! You just won't have the range.
@Ann M. : Montague builds are so cool. Any bike designed by paratroopers definitely gets my approval. I haven't found that the D-series is quieter than the S-series, however, it's still quieter than everything else, and it has a more guttural sound that I find quiet satisfying.
@Crazy Lenny Ebikes: I love super moto x tires. Hope they come out in retail at some point. I actually went small block eight front and rear. It'll have fantastic road and off road characteristics, but 30-80 psi mirrors Schwalbe balloon styles.
I'll create a link for the karate monkey soon. I've done some silly stuff to it.