Is healing potency really that much more useful than mind? Personally I much rather have healing potency and magic accuracy.
Healing potency is a lot more useful than mind.
To put it one way, you only get 1 heal potency from about 4 or 5 mind... (Or that's how it's been when I've briefly tested it out at least)
If the rates for accuracy are the same, then a single heal potency and a single magic accuracy materia will be more useful than roughly 4 mind materia.
I'll test them out a bit later on.
Edit: From some basic testing (equipping and removing several pieces of gear with different mind stats) it seems that you get 1 magic accuracy and 1 healing magic from every 4 points in mind.
In theory if you're using 2 pieces of maxed mind materia you'd get more magic accuracy than a maxed piece of magic accuracy and healer's hands but would be missing out on half of the healing potency (With examples using maxed materia, is it really worth sacrificing 10 heal potency for 1 magic accuracy?)
Of course mind is a good choice if you don't want to specialise in one stat and only fusing one piece of materia on to the gear, but otherwise I think it's best to use one of the other materia if you have the option.
Also, feel free to do some more in depth testing of what the exact stats you get from mind since I may be off. :P