"I guess I agree with Akhilesh that cutting out some of the signal to add weight to other parts seems to be a little inconsistent with the point of using a single driver."

There is no question that your statement is indeed the generally accepted philosophy for single full range drivers. Personally, I don't like living by strict audio rules just because it is the accepted practice. If you want to advance your system's performance, then you need to think out of the box and try a few things that are "wrong". As for the filter and Lowthers, you can always put back what the filter attenuates (notice I did not say removes). With my Fostex systems, there is nothing you can do to add the extra detail of the Lowthers.

Martin