Rubies are cheap as you know, so quality isn't great...
A fair few fellow 501st guys use the Rubies/Don Post Scout lid, but needs heavy modification to make it look anywhere good. And yes, they do warp easily. Size is faily good.
Fett... hmmm... IMHO, stay away..
One of the old Don Post deluxe lids was excellent, but as far as I know, Rubies hasn't come anywhere close.. Way too small as well.