Sorry but I'm with Sonic Wave on this one, the messy isn't Marth's style, also he IS a prince whether he eats two or ten square meals a day and as you can figure, of course he probably upkeeps his appearance (else he'd have some sort of facial hair by the end of FE1) and agreeing agains with what Sonic Wave said Marth was the one who set the standards for all the other FE lords (which is probably why they're so similar in everything else to Marth also) Ike being the only exception, strictly because he's a non-lord. Even looking at the personalities, almost all the other lords are similar to Marth. Fighting style also (especially Sigrud. "No that's not the falchion that's... my sword..." >_> <_<) which is, again what makes Ike so different. Lithe, rapier using Lord to hard-cut barbaric broadsword.
This also pretty much shoots down the "Ike is replacing Marth" argument, yet again...