The midi range, not the tweeter, is the most important driver in a speaker.

It's more interesting to discuss in term of midrange driver size.  Some people prefer smaller size mid for speed and clarity.  Mine has to be at least 5in large so they can better integrated to the 8in. bass at the low frequencies for example.  

Also I prefer the mid not playing at high frequencies where the tweeter should be playing on its own.  I would say 7KHz is the cutt off where the mid shouldn't interfere with the tweeter playing after this.

Sure if you have a 3in. mid that can play at much higher than 7KHz but then it would compromise the low frequencies.  It's all a trade off.  

What can I say Erik, you are absolutely correct!  

No, 100% disagree.  Every mid I've heard since early 70's i hated. 
I avoided all 3 ways with mid ranges past 40 yrs. 
I am sticking with  a  MTM, allowing the lower W18 to act in low fq.s the upper mid bass meeting the Millenium tweet which is really a  true Mid range/Tweeter. = you get 2 drivers in one. 
IHow is this possible?
I just understooda   few weeks ago, after owning the Thor MTM for now 17 years..The Millenium employed the latest technoogy at that time Neo magnet. Which is XXXX times more potent vs your old regular magnet tweet. 
The upper W18 carries the low mid fq's up to meet the low FQ's of the Millenium = No need fora  old basrking/coughing/blaring midrange. 
I HATE all/every midrange. 
Millenium, the finest midtweet ever designed. 
Finest tweet every tweeted. 
paul
the honest stereo review guy

@erik_squires ..Agreed, and my RTA’s and eq’s do as well. I’m monitoring both line And the ’room’ (the latter w/a calibrated mic into a ’stand-alone’ unit). Mid-range, as approached by the bulk of the ’conventional’ speakers marketed, is where voice and instruments Are....

And, Yes, the crossover is where the crux is....*serious stare*

And, this is Why I’ve moved to a digital xover since I don’t rely nor listen to a ’one box wonder’ for my ’listening distraction’. ;)

My ’reference’ amt’s will reach down to 500hz; below that, the sub picks up @ around 150hz.

That leaves a very important gap that’s important to infill. Currently I’ve using 6" with a 6" passive, quick enough to keep pace with the amt’s. And be x-overed to not compete with the subs.

The big issue for me is a woofer that’s fast enough to keep up with ’what’s above them’. *L* We all have our ’issues’, I guess....;)

...and I’m just an ’outlier’, anyway...
...and my Walsh are an entirely different animal...as well....

But, that’s what ’memory files’ is for...*L*

(*ah* Re 12/1 @ 12:04am: One has to watch what one ’trolls’, even if only in jest....’flame wars’ start with less.... ;) *G*)

To think about it, everything else being equal, the mid probably is more important than the tweeter.  But what's more important is the xover.  The designer will ultimately be the final decider as to the final sound.