only downside to powder coating is if it cracks in the wrong places it can hold water, if you are a bit of a cleaner or look after your bikes you should be able to notice any cracks/water before it rust a hole in your frame.
last thing i had P/C was an RD, in white just stuck peices of masking tape in the holes and it was fine, i think the finish can vary based on how fine a blast grit is used, and how well the painter gets it off the gun, if it runs you gotta start again, whereas painting you can sand out and blend.
I think if your racing i'd powder coat to stop all the roost marks and rocks in the down tubes, but if your restoring go with a acid dip and paint.
horses for courses me thinks