You die
Couple things to note--
Bad idea. Especially in the later levels.
What if the person you're following decides to lead you into a nice big group of snow men?
Poof.
And, fighting really weak enemies is near pointless--each level lower/high in CoH is around a 33% change in XP (down or up, respectively)
So, if you're fighting enemies to where there is no risk (2 levels below..) you're getting almost no XP.
Good idea though, but MMs are a bit too gimped.