Thanks Ed! Since that Photodiox adapter is out of stock everywhere I'll soon know what the Kipon adapter does.
All my 645 lenses have aperture rings so it seems like that should simplify the adapter mechanics. I'll report back once I can try it out.
I never got anything wider than a 35mm on 645 so I also bought the 32-64 native lens to take care of that range. I was planning on using the adapter mostly on longer lenses so that should be ok.
Once my finances are recovered I'd consider that 23mm native lens too. Still less expensive than the 645 25mm last I looked!