I am very new to both turn based 4x games, and FE in general, so this might just be a newbies perspective, but I want to talk about expanding. I have played Civ V and one feature I liked about that game is that I do not have to expand, that I could have a powerful empire with four cities. Taking that strategy in FE though, has led to me getting destroyed by the AI. My current game I have adopted a mass expansion, basically having one city only making pioneers, and this time the AI is cowed, even though I have less military than my previous games.
In general it seems to me that there is no penalty for making pioneers and just cranking out cities. At least I haven't found one, with this current playthrough being my best yet, simply due to me having so many cities. I am correct in thinking that mass expansion is the best way to play? It seems to me that whatever win you are going for, mass expansion is the way to go, which makes your early game at least be fairly similar.
I am not entirely sure what the solution could be, or even if this is considered a problem. Perhaps making all the buildings you can make(which seems a ton more than Civ) build faster, or allow instant purchase on units, rather than just rushing.