As for the Graflok, I'm just having trouble finding a 120 back that's not terrible for springback.
I've got an Adapta-A-Roll 620 and it works pretty well. If you can find 'em (or make 'em), there were masks for it to shoot 6x6 and 6x4.5, but it's natively 6x9. You load it by the arrows, like some 120 backs, and advance by ratchet clicks. It needs a 620 spool for takeup, but mine will feed from a trimmed 120 roll. Best of all, it slips under a spring back like a Horseman roll back that costs five times as much. And, like most medium format roll backs, you can also load it with 35 mm (and unload in a dark bag) to get sprocket hold panoramic images, 35x85 mm.
