Just to follow this up (if anyone happens to be interested...)
I bought a pair of the MT90's - absolutely excellent, everyone should have a pair
Comfortable both on and off the bike, you can actually walk on wet rocks and stuff without falling on your arse or mincing around like some big nancy.
Waterproof too (of course) - I'll probably end up wearing them most of the year, it's never that warm or dry here.
Re. sizes - I wear a 42 walking type shoe and 43 walking boots and I'd say that the 43 MT90's are a perfect fit for me with room for a slightly thicker sock if I want.
Anyway, 5 stars for these.