It seems that most people view powder coating as more durable and longer lasting than paint as well as being slightly cheaper.
It most likely is but for the purposes of a MTB is it really necessary?
As I said my two day old 2 pack paint job took a big hit from a tree trunk without any damage and I was told two pack is very sturdy.
So to me it seems that Powder coat has a more limited range of finishes and colours, "could" and this is very loose cause the frame to weaken and is a bit patchy in terms of who does it as some PC's are better than others.
Windridge coatings were at the bike show and I've lifted this from their site
Can my bike frame be powder coated?
Any metal that can withstand 220 degrees Celsius can be powder coated, this includes the following:
Conventional aluminum and mild steel frames.
Frames made from Reynolds 525, 531, 725, 753 tubing that are often silver soldered or brazed.
Chromium-Molybdenum Steels have a high strength to low weight ratio but are still predominantly steel.
Titanium in its unalloyed condition is as strong as some steels but 45% lighter.
We cannot powder coat carbon fiber frames.
A spray job offers better colours IMHO, tricky finishes like metal flake or pearl and is definately benign. I know what I'd go with.