So Dhruin is the mystery artist? [Edit: Or were you just referring to the cover art for AoD displayed on RPGWatch?] Very nice work - congrats! As for the consistency issue, rather than fixing the mountains, I would suggest giving the currently photorealistic bits (particularly the craters) a more stylized, hand-painted look, which could be achieved simply by running a filter such as the Gimpressionist over them.
I just realize that MF seems to have done something like this on the Codex thread, which, IMHO, looks great. Will the actual in-game map be done in a similar style, or will it have even more of a hand-drawn feel to it?