95% of my flights are on BA metal and their carry-on dimensions are (H x W x D):

Hand Luggage: 56 x 45 x 25cm
+
Laptop/Handbag: 36 x 45 x 20cm

So slightly more than the standard IATA limits.

The Rimowa Topas line has a couple of bags that would seem to max-out these limits:

Cabin Multiwheel: 56 x 45 x 25cm
Mini Trolley: 33.5 x 44 x 19.5cm

Can anyone here confirm the exact dimensions of the Cabin Multiwheel as I am not sure if the quoted dimensions include handles and wheels?

I have the Cabin Trolley IATA which is quoted at 55 x 40 x 20cm and I just measured it at exactly that including handles and wheels.