Topgunz,
The crossovers listed cross over at 4000Hz. The tweeters will play down to there, and roll off below that. A good 5.25 or 6.5" driver will play just fine from 40Hz to 5000Hz.
The idea of just using 4 mids and 1 set of tweeters is something I play to do as well and should work just fine. If you don't like how it sounds after you install just the midranges, you can always add the rest later.
Aaron
