Dan my HT/Recroom is pushing 900Sq Ft with 9ft ceilings and my 60's go plenty loud with my Denon 2805 AVR. I was in high school back in the 80's metal days and also like it loud, and I am totally happy with no plans to upgrade soon. I know Wid thinks I need m80's but looking at the graph, other than a slightly better bass response, the 60 graph looks flatter.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85