Pioneer HPM 900 epiphany

I've asked before about a crossover upgrade for the HPM 900, but after thinking about it from the perspective of "how do I make this a better sounding speaker" rather than "how do I leave this speaker near stock and make it a little better" I realized part of the problem is right in the middle - it has a very good woofer and a very good supertweeter and then very dated mid and tweeter. I think the best plan to make it a better speaker is to convert it to a 3 way using a full range 4" driver to replace the current mid, and just remove the old cone tweeter. Then make a 3 way crossover that crosses at around 300 Hz and 10 to 12 KHz with good quality components. I have too many projects on the list to get to this soon, but I'm thinking about using this for the mid once its available again:
Tang Band W4-1337SD 4" Titanium Driver | Parts-Express.com
I'd also plan to add some internal bracing and maybe some Acoustistuff, but keep most all the mods as reversible as possible. Comments?