Have you tried to find someone nearby that you could get an audition from? This way you could try your own music and see if you like it. I haven't found any problems with metal or another genre, as long as it has been recorded well. Axiom's are just very acurrate and will show the flaws in any recording but good recordings sound incredible.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70