My experience is that if you go on the tight side, the engine will never rev well, it will feel tight. If you ahve them leave it on the loose side, it will rev freely, won't feel "not broken in" or like a cold motor all the time..
You really need to send the pistons to the shop, if they are good at what they do, chances are, they will get it right. This is not exact science... It's preference more than anything.