People worry about how "thick" the powder coat is and how it may slow down the convective heat transfer... but I really don't think it should be a problem. We're still only talking a few thousandth's of an inch.
$1100 does seem high but there is a lot of labor there. If he is doing each piece separately then he has to mask off all the bearing surfaces, oil galleries, gasket surfaces, threaded holes, etc etc etc.
I was quoted $750 to do my frame, oil tank, swing arm, front caliper, misc brackets, chain guards, etc etc. That price is high compared to what I have heard but around here the market is inflated from lots of mining companies using powder coat on their industrial equipment because of it's durability.
I chose to spray bomb mine after I got that quote and I'm pretty happy with the results. Powder coat would have been nice though...
IW