I think many metal historians (yes, such a thing exists) classify AIC as a metal band in the subgenre of "Grunge Metal". Most classify Soundgarden in the same category. I personally consider AIC a metal band.
Ironically, I didn't get into grunge until MTV Unplugged:
AIC started out metal, though a couple of the guys previously played in a funk band. Their first big tour was called "Clash of the Titans", where they opened for Anthrax, Slayer and Megadeth. No one had heard vocals like that before in a metal band. They were booed on their first couple shows, until one night they were going back to the bus and a crowd came around them. They thought they were gonna get in a fight, but the people in the crowd were coming to give them respect for toughing it out.
Back in the early days, all those bands were forced to keep playing the same stuff when they were mainstream. In order to do different stuff, they had side projects like Temple of the Dog, Foo Fighters and Mudhoney. Today, they have definitely evolved similarly as Soundgarden, with their own distinct vocals:
What's notable is that they use a lot of exotic tunings and time signatures, like 5/4 and 7/4 (the first half of Pink Floyd- Money is in 7/4), and are as rigorous as classical musicians (just like Pink Floyd).
Tool is rigorous like that, too:
for drummers:
for bass players:
I must have forced him to listen to Symphony X a dozen times, but he didn't put them together. And we've seen Dream Theater many times...
