I've actually never played MoM (gasp!). I'd personally prefer that He keep in mind the things that made His mod successful, Amen.
Like very different factions and strategic depth.
Because, as far as the base for FE goes, I think that it was a decent fantasy wargame, but just doesn't have the heft in game mechanics to be a great 4x TBS. Only my opinion, of course, but the way that culture, religion, civics, and diplomacy interacted in Civ4, and thus FfH2, was exquisite, and I haven't seen anything that leads me to believe that FE will have nearly the same amount of strategic depth.
I know that Stardock hates this kind of post, but I think that it's a simple fact that the less nuance there is in a strategy game, the less long-term replayability it's going to have once the Gee-Whiz factor wears off.
That is all, feel free to ignore the sentiment, if you'd like.
Edit: Although I'm not convinced, I'm still cautiously optimistic.