Powder coating is the best way to go - for durability. If you're trying to match a specific color, you should stick to paint. If you're worried about weight, stick to paint. If you want the cheapest, easiest way to go, stick to paint. All that said, powder coat those donuts!
The weight difference will depend on the technique used. Obviously, if you're painting over the wheels and use multiple coats of it, the weight advantage will be minimal at best. If you strip the rims, repaint them, then you'll save several 10s of grams in weight versus powder. Woohoo! Powder will be a bit heavier, but not enough to worry about IMO. Unless you're peterd10r, then don't stress about it.
The powder will cost more than paint though. Not in terms of the material, but you have to pull and replace the wheel bearings. You can mask off and paint over/around the current ones, but that's not an option for powder. So the cost goes up in terms of that.
or10r has your contact info for all that stuff! Herb will get you squared away on it!