I test rode a Ramblas today on the street, but with a fair amount of climbs. It rode very well, although I agree I'd prefer to have a rear suspension. However, I've done plenty of mountain bike riding in the past with a hard tail. I'm 5'8", but long waisted (30 in inseam), and both the medium and large size fit me pretty well so I'd probably go with a large since I felt a bit too upright on the medium (although a handlebar extender could be added).
I currently have a Specialized Turbo Levo and the SRAM brakes (four piston) and shifter (12 speed) on the Ramblas are just one grade below the Levo and feel very similar, although the shifting was a bit clunkier on the Ramblas (maybe because it's a new bike). Strangely, the Ramblas motor (rated at 100Nm vs 90Nm for the Levo) seemed a bit weaker when climbing but the three assist settings are fully programmable and I think the Ramblas default is at 80nm (based what I think I saw on the review here) instead of 100nm although I could not confirm that. The motor noise on the Ramblas is noticeable, but not too bad IMO. The Brose 2.2 on the Levo was quieter when new, but it's quite a bit noisier than the Ramblas now. I tried getting the whining motor on the Levo replaced under warranty but Specialized said it was "in-spec" and denied their warranty. A replacement motor is about $1300. I can get a Ramblas for less than double that due to rebates on new e-bikes available here ($450 from Colorado and $150 from my electric company). The other thing I liked a lot about the Ramblas is I was told a replacement battery is just $500 compared to about $1300 for the Levo (both are just over 700 Whr). At least my Levo original battery is still going strong.
Anyway, like the reviewer here, I was impressed with how nice the bike is for the price and for being a brand new model. I have to agree that there is a big potential risk in getting one now because of the unproven motor. My Levo motor still works well, but the whining got loud at around 600 miles (I have 2200 miles on it now in a year and a half of ownership). If I got a Ramblas I'd probably look at replacing the spring shock with an air shock although the stock shock felt OK to me on the test ride.
For me it comes down to the motor, including how much faith I would have with a new motor from Specialized. I've read the Brose 2.2 still has a lot of issues and it was sad that mine got a problem after just 600 miles. My guess is Aventon would take care of any motor issues since their reputation would be at stake, but who knows?
