I think the Hedge-Mage is just a bad card. If I'm splashing white, I have access to way better options. If I'm mono-red, he is a RR1 Manic Vandal essentially (yeah, I guess he has the MAY clause, so slightly better but still pretty bogus).
The only upside is if you can three for one with him triggering both halves. And if that happens, yeah he's good. But I need two mountains and two plains, so he's more like a turn 5 play. And on turn 5, I'd rather play something else typically. Oh, AND my opponent needs both an artifact and enchantment in play. I just can't imagine that happens often.