I don't think Devon's Coastal Climate is quite typical of the rest of England.
No, M Itinerans grows much faster than M Basjoo. I fact M Basjoo does not grow to well for me or perhaps I am impatient and just find it too slow.
I have to cut my M Itinerans down to about 7 ft each spring or the wind destroys them, but apart from that I find them hardy here. They must be "pruned" spring rather than autumn because they don't overwinter well without leaves. Perhaps this is where UK growers are going wrong. They keep their leaves all winter, unlike basjoo. With M Itinerans, if you lose the leaves you often lose the plant and they are actively growing all winter.
Having said that Monsterosa Deliciosa is winter hardy here, so I guess it is not surprising that M Itinerans copes (except for the wind if it goes too high).
I can't find any good photos of any of my M Itinerans on my website, but have just drawn a scribbly circle thing round a baby M Itinerans on a general panarama of one side of my garden (There are also two M Sikkimensis pups just below the Alocasia):-
Oh, and just to the left of my scribble circle is M Helen's Hybrid pup.