To the original question, I think an 18SX, given the proper space would be a very good daily driver setup.
I also think however, that you'd have pleny of power to push those L7s assuming that impedences match up and you're able to wire the subs down to a 1 ohm load. I've heard a few setups with a directed 1100d pushing 2 L7s and it was plenty of power to get them going.