I do agree with you and completely understand what your saying.. I was just stating an example thats a little more on the extreme side (as most people choose between 10" or 12", or 12" and 15"...not 10" or 18"). And there are alot of people out there that do lack in the upper sub frequenices (70-100Hz), where a 10" sub could be allowed to be crossed over a little higher, and make up for the lack of punch from the mids. A 10" of the same brand/model will typically play into those ranges more accurately than a larger 18" driver.Again, not saying that a drivers size has any bearing on its SQ, just that a different size driver can play better/more accurate at certain freqencies...hence why we use 8"-18" subs, ~6.5" for midbass, etc. So, it may make a difference in the overall SQ of a system, should that system be lacking in a certain area.