I have a black powder coated A-frame and love it!...Goes well with a Black Rib!
...I had mine done before it was polished...which is a very labour intensive processes in itself!!!
Especially on a large Double.
The fabricator/maker who I know personally was more than happy to powder coat!..The BIG thing is to SHOT BLAST and 100% degrease the SS to form a good "key" before Powder coating
PM me if you want details....but yeah it works well if done properly
Not sure but I'd think Alloy may be just as easy...or easier.