Glad everyone loves thier RB67s.. I won't shoot anyting else these days.. I'm in love with my huge negatives. I like hand holding mine n have no trouble.. it is jsut a matter of getting the hang of it. I do use an ETRS for street shooting but even then I still prefer the wonderful 6x7s of the RB.. still no comparrison in details n tonality.
I also repair RBs for many years, but only the mechanical RBs (no RZs) n work on all the older lenses (No K or newer series).
That hand grip looks really nice.. never had one, that can be a real asset.. does it hurt your wrist after carryig it for awhile? I tend to hang my camera on the neck strap over my head n a shoulder. That takes the weight off it so it virtually is suspended just at the right level when using a chimney or WLF. When using the prism I have to support it but still not a problem after working with this beast for many years.. your arm tends to get stronger with experiance... still a balancing act of a sort to take the weight off it.
Enjoy your new toys!