Anyone ridden/got one? Only a few thin website/magazine reviews around.

Don’t know......
I’d never want to own anything that looks so darn ugly Handle-bar stem looks like it was cobbled together by a drunken plumber.

LOL

Funny, to each his own, I guess. I kind of like the Mezzo look.

The Mezzo seems to be a good fit for a lot of people. I personally like things designed, not engineered. The "drunken plumber" theory is quite funny: The mezzo wasn't for me anyway, but after you said that I cannot look at that stem without thinking there is something very wrong with it! LoL.

I think the Mezzo's stem design is quite clever. Rather than go up, then out, it simply goes out, then up. This enables a tight fold without nearly the compromises that Brompton needs to make.

I think design aesthetics are often bunk. Perhaps disagreement with the aesthetics of the stem might stem from spending one's life seeing stems go up, then out; or just up. If the world only had Mezzos, surely (say) a Brompton or Tikit would look ridiculous.

This is the same effect that recumbents have on people. Recumbents are in many respects superior bikes; certainly much faster, more comfortable, and safer with forward lookahead. But they look ridiculous because people are so used to seeing, for 100 years, a largely inferior design, and it's burned into our neurons as the "better designed bike".

Don't know about the D10, but the weak point of the Mezzo were the gears. I think AtoB wrote something like - this could be a Brompton killer if it wasn't for the gears - but this is not an exactly quote.
But if you really want to know if a bike fits you the best way is to test it . . .

Old data at this point I think. Mezzos have (I believe) a 349x35 tire. The D9 is 54 x 11-26, which yields 33.4 to 78.9 gear inches. Basically similar to the stock Tikit. The D10 is 56 x 11-28, which yields 32.1 to 81.8. The D9 doesn't even have a Capreo any more, unlike what A2B thinks. A2B really needs to broaden and update that buying guide. Highly British in perspective, and a bit dated.

The increased price of a D10 over a D9 or D4 does not represent good value IMO.

The noticable upgrades are;
1. The frame is around 1/2 pound lighter?
2. The chain wheel is 56t rather than 56, and therfore a bigger chain guard is used.
3. The rear brake is V brake rather than Calliper.
5. 10 speed rather than 4ihg or 9 with mech.

I decided to upgrade a D9 instead

See the "upgrading a Mezzo thread" or "Mezzo dualdrive conversion"