I didn't know GoDaiKin was released in Japan? Or did you mean the various Popy toys that were assimilated into the American GoDaiKin line? GoDaiKin is a combination of Popy's later Chogokin and Popinika toys, as well as a few others. I've never seen any of the originals, so I can't really compare.
Actually, that was the "power up" version that included the armor, I have it as well and I think it is totally killer . The DX Chogokin released by Bandai was identical to the Godaikin, with the exeption of the packaging, insructions, and catalog of course.