Of course, I'm curious: take the case of the Epik Empire and the LFM-1EX. From 50Hz on up, the Empire has a big output advantage. Epik's issues aside, would you qualify the Empire as being significantly better than the LFM?
Everything else being equal, yes, a sub with more output above 50 hz is going to be better. If you can get it, there is no reason not to have it. For starters, if you have dips above 50 hz, you have more room to EQ the response down to flat without losing output for the entire subwoofer frequency range. Secondly, there is nothing wrong with having extra headroom in a certain range; it may not play flat when brought to its limits, but the extra dynamics in that range will still be truer to the dynamics of the recording than a sub that just can not cross that output line at any frequency. Third, there is a lot more bass material above 50 hz than below in most movie and music recordings, so if you can have extra headroom there, that is the region where you want it.
