I'm a longtime Rimowa user, and i agree there isn't a 50L+ Rimowa that works reliably as a carryon. For international business and first travel I've seen folks take the 45L rimowa multiwheel on board but it's very risky...the problem is not the airlines (which will grant f/b passengers some latitude) but security.

If I really need more capacity in a carry-on I take a Louis Vuitton Eole 65 which has about 50L capacity. The damier graphite is understated luxury, and there are a lot of really nice design details on the bag that reflect LV's heritage as a luggage company. Don't get the cheaper models without rolling wheels as you will curse the gods walking to a faraway gate in Heathrow or DFW.

Here's a US link but LV is much cheaper and tax free in Europe:

http://us.louisvuitton.com/eng-us/pr...raphite-008172