Do the 18's fo sho, just because they are so sweet to look at and everyone is running L7's nowadays.Heres the scenarios,
2 18" SX, 14 cubes, powered by two MD2s
2 15" L7s, Huge box, on two MD2s
4 L7s, huge box on two Orion 2500ds
The new l7s shouldnt have any problem handling that power. Iv ran 2kw to the new l7 15, and its taken it for months without any problems. They are beasts...2 2500d would kill you electrical
not that you need 2 2500s for 4 L7's
they are only 750rms apiece