I have a question. Your list of mervin recommendations is (more or less) a list of boards from softest to stiffest.
Erm, not really. T. Rice is the clearly the stiffest deck on the list - only included because the OP was specifically asking about it.
The rest of the list is made up of fairly similar mid-flexing boards, with only the the Magic and the Attack Banana being somewhat stiffer than the others - and I had those at 1 and 4, respectively.
I've never ridden japan, so what makes the snow/terrain there especially suited to soft decks?
Up here in the PNW, especially on wet days, you really need some beef underfoot to handle the heavy stuff.
Hokkaido pow is generally light, dry, and fluffly. You do not need a beefy deck for this at all (decks do not 'fold up') but you really do need float (through shape, surface area, profile - or a combination of all of these).
That is why the Skate Banana (possibly going up one size) is an excellent choice as all-mountain board here from among the Mervin twins.
But the OP was really interested in CRC, so I mentioned the two Mervin boards that have the most rocker/float with this profile (the Attack and the Magic) - although they are both much 'more' board than needed.
The rest of the list are very similar in terms of float and flex and there really is not much between them. However, as Shred pointed out, none of these will be great in pow - awesome boards yes, pow slayers no.