Sorry OP, this threads gone everywhere 
, too much excitement, I second your thoughts on an all out classic monitor design. The berylium scan tweeter and revalator woof would work nicely! The new x series in wave guides will be interesting. Curious how the tweet will compare to other wave guide designs. A lot of those use pro audio type tweeters.
I don't mind the thread moving around a little bit. There are a lot of new and interesting new designs being discussed.
Don't get too carried away with drivers using exotic materials. That doesn't equate to better sound. And while that tweeter may boost a Beryllium dome, the air cavity behind it is quite small and the break up or ringing in the upper ranges is fairly substantial.
A fancy frame doesn't buy you anything either. The best thing about that frame (Scan Speak Illuminator woofer) is really how open it is to the air flow on the back side. However, it is still a metal frame and still rings when excited. And in other ways it gives up a lot to our new woofer.
Adding a wave guide to that Peerless tweeter is a pretty big deal. This allows a crossover point in the 1kHz to 1.2kHz range. This is huge. Allowing a tweeter to handle 1kHz to 2kHz verses a woofer is a REALLY big deal. The speed and resolution levels are not even comparable.
Regarding a woofer handling that range. The movement of the cone at that wavelength is fairly short, but at the same time the woofer is having to handle long exertions of the lower wavelengths. So it is a big compromise. That compromise of handling longer exertions is what holds back most two way designs compared to a three way design. The mid in a three way no longer has to handle the lower wavelengths. The result is cleaner mids. The same goes for ranges above 1kHz. A woofer no matter how good is no match for a good tweeter.
Plus the Scan Speak is not all that great for 1 to 2kHz either. The comparable sized Scan Speak Illuminator woofer has a third again more moving mass than my new woofers. The heavier moving mass can be an advantage in allowing the driver to handle ranges below 60Hz or so better. But it can be a real disadvantage in the upper ranges. The heavier moving mass also takes away sensitivity. Plus that Illuminator woofer has quite a bit of upper range break up that can be a big issue. The Revelator woofers are in the same boat. To match the light weight moving mass of my new 6.5" woofers you have to drop back to 5" Illuminator or Revelator woofers. And then your sensitivity levels drop off into the 83 to 85db range. After 5 to 6db of baffle step loss you are in the 80db or less sensitivity ranges. That's not my idea of usable ranges for a mini-monitor. That's the problem with using off the shelf and generic commercial drivers rather than purpose built custom drivers.
