I hear from people who have had good powder coating, so it must exist. I however have never been so lucky. Even the frame on my Commando, on which the finish is superb, still has the same floor that all powder coating I have ever had done has: it is too thick. Some of the more intricate components were almost un-fit-able, the dimensional integrity had changed so much.
Powder coat can be applied to have a fantastic finish. It is also extremely tough. But care must be taken to ensure the company really, really, knows what they're talking about and really, really, understands the difference between motorcycles and garden furniture.
I went with a company that was recomended by some who's opinion I value highly. They specialise in motorcycle parts. Their 'agent' (a Harley outfit)went to great lengths to pursuade me how much they understood motorcycles, yet even so, they still applied the damned stuff way too thick!
So my summary is, powder coating is very probably perfectly OK in principle. But the end result is completely down to the guy pulling the trigger on the day your job goes through.
If he cocks it up, there is little you can do about it!