Thye look cool in Purple! But how about that Trophy blue colour they paint modern MGs. Having painted a door before the real pain is painting everything inside the car as well!
I resprayed mine.. but in the same color.. looked new (for a while) I think you may have to let, erm.. your insurance(?) know when you change the color?
It all depends on the 'look' you want... if you want it to look good, get it done at a bodyshop... if you want it to look like its all your own work... DIY.