I have used Zoerk and Novoflex adapters.
(To put Hasselblad lenses on 35 mm cameras)
The Zoerk thingy was a too tight fit, and i had to machine it a bit more to make it usable.
But i wouldn't base a general 'verdict' on one sample.
The lens catch releas button on the Zoerk is (quite literally) a pain to use. It is a bent bit of metal, with rather sharp and rough, 'serrated' edges. Not nice at all.
The Novoflex was better machined, and easier on the fingers. Like it better.
Both my adapters are rather old, and since i bought them the thingies may have been changed.