Well, I think there simply is no way around going 64 bit for a 3D software these days, so the sooner the better as far as I'm concerned.
Some other 3D software doesn't even come in 32 Bit anymore...

I'm usually not doing supercomplex models but need the data rather finely subdivided for closeups, and even that is getting problematic in some cases with MoI.

So I personally would vote for 64 Bit first, everything else later ;-)

But that's just me.

Cheers,

Tom