True, I suppose the defintion of "metal" can be debated, but I still wouldn't call Aerosmith metal. I definatly wouldn't call Mama Kin or Train Kept a Rollin metal (Train Kept a Rollin is actually a traditional blues peice), but Round and Round has some metal qualities. You're right when you say Slash was influenced alot by them, but then, I wouldn't call Guns N' Roses metal either :)
I'm not that much of a metal fan, but when I think metal I think Ozzy, Megadeth, Metallica, bands like that.