Would B&W804 + high quality sub =B&W802?

Question

A couple of questions from my pondering the best way to create a combination HT/music set-up... Would a high quality sub, say a B&W ASW 2500 paired with B&W 804s produce a sound comparable to B&W 801s or 802s? (this would obviously provide a big $ saving!) In a multi-channel music set-up consisting of B&W 804s, B&W HTM1 and B&W 805s, would playing all speakers "small" with a sub relieve the need for identical speakers for best sound since the tweeters and mid-range for all 5 speakers are very similar? All opinions but especially direct experience greatly appreciated!