Jon
I am a better brazer than arc welder.....But I found out today that I am out of practice and there will not be any close up photos of my welds.
As for which will last longer, I would think that if done right either should last. I have read some posts on PlanetChristmas where people have sent their wire frames for powder coating which would be very resistant to weather (big $$$$). Commercial websites state that their wire frames are powder coated also. So I will be priming and painting.
Here is a link I found pretty interesting on powder coating
http://www.homemetalshopclub.org/projects/powder.pdfI suppose its like anything else the cost of the equipment to start up. I don't think my wife would like me using the kitchen oven to bake (curing the coat) the parts!!!