I didn't think I was super crazy about it either, until I brought out all my old MSIA figures to get ready to sell, and I noticed that the God Gundam easily had the best proportions out of any of the figures I had. It really gave me an appreciation for the design, and I thought, like you said, that an RG frame would compliment it really well.
I'd definitely buy one if they made it, and I'm not a huge G Gundam fan.