I just got my 645 adaptor in the mail for mounting V lenses on my Phase One XF and I wish I had done it sooner... So far I am impressed with the quality of my 50 CF (non-FLE) and 160 CB (A very under rated lens IMHO), although I haven't done any in depth testing.
I wish there was a way to mount them on my RM3Di so I could get some long lens options, in addition to getting some limited movements, without needing the XF or having my Sironar-S lenses remounted.
If only Arca would sell the parts for the RM3Di lens boards, as I'm sure SK Grimes could marry a Hassy V mount to one of the boards. I wonder if I sacrificed one of the short "remove for rotaslide" spacers that I'm not using, if it could be done somehow...... hmmmm.