Joeb -- Before rushing out to spend money on new equipment, you ought to try a bit of repositioning first. Depending on your room, many things can play into how much bass you receive in your listening position. The general considerations usually are:
How far are the speakers from the rear wall? The closer to the wall they get, the smaller the soundstage, but the more pronounced the bass.
How far are they from the corners? Generally, moving the speakers to corners will increase the bottom end by reflecting the bas outward.
How are the speakers coupled to the floor? My ProAc's are coupled to the floor using 2 inch spikes, but I've noticed that when placed directly on the floor (carpet over hard wood), I get quite a bit more low mid bass, in my case to the point of making the sound muddy. You'll certainly find different results with the B&W's, but playing with the coupling is worthwhile.
How far apart are the speakers? I can't speak for everyone's setup, but in mine the closer the speakers, the more pronounced the bass. This, I believe, is due entirely the the focal point of the sound and should vary from room to room. However, I've noticed that a foot difference in separation makes a huge difference in both the listening position and in the bottom end I get. Also, when the speakers are placed along the long wall in the room (so I have a shorter listening distance), I get a huge amount of bottom end relative to rotating them 90's.
I've listened to the 804's and while I wouldn't consider them bass heavy, properly driven (as your's seem to be) they always seem to provide more than enough bottom end. Anyway, it doesn't cost much to push the speakers around the room and see if any changes in position solve your problem.
-- Ken