Obviously you need the 45H-1 with the 5x7 back so you can use 6x17 -- you know you do!
But actually, while I am a fan of the type of camera the 45H-1 is (non-folding, keep the lens on), the focusing system is very different from the 45N-2 and there is some weight gain with the 45H-1. I'd be hard pressed to decide between the two, but for 4x5 and 6x12 use and saving almost a pound, the 45N-2 is a good tool. Using 5x7 just horizontally on the 45H-1 body is not appealing to me, anyway.