i wouldnt reccomend it, you'll get two kinds of sounds from them, the ported may be a bit louder but it will definately be sloppier than the sealed subs because the bass will carry a little more ported...
id think the ported would negate the fact that you have two sealed....seeing how as it may be a little sloppier and roll on a little more, cancelling the tightness effect that sealed has
i would go all one way or the other if it was me...
Heard someone do it. Trust us, it's all or nothing. The loudness of the ported will overcome the sealed. If you cut the ported subs off and ran only sealed when you want SQ, and vice versa when you want SPL, I could see where you're going, THAT would be the best of both worlds. If you want to know if it'll sound better firing all at the same time, not really, just a little louder, but still sloppy.