Just joining the chorus to say that I just received two Mautto straps, one for black RH and the other for black ME silver. Both seem to be excellent quality and match well.
I asked for and got swatches of the black options beforehand---free if you're in the USA! In the end I used the Low Pebble Black for the RH black and standard Black for the ME. The ME was the harder match---it's much shinier than any of the options, and Black is the shiniest, but doesn't have much in the way of texture. Honestly, I could have gone with either leather for either bag, now that I have the straps in front of me---but I'm happy with my choices.
Fellow City owners, I highly encourage trying out longer straps! I had never really been a fan of crossbody bags (too long when I don't want to wear them crossbody), until I discovered that the Givenchy Pandora medium is EXACTLY the right strap configuration for me (long enough crossbody, short enough to wear on my shoulder) and I wanted to be able to do the same with my Citys. And I love the way the city drapes when it's hanging lower.