Help Choosing Subwoofers

I have a 7.1 home theatre system consisting of (2) B&W 805S (Front), (2) HTM4S (Center), (4) SCMS (Side & Rear). I currently have (2) ASW675 as subwoofers (I upgraded from a 600 series system a while back … except these). I have a couple requirements that exclude the ASW825 which was my original choice. My room is fairly large so I will probably get two subs again - the 675's just aren't cutting it on "larger" material. I would like something that goes lower and has more output (punch); that being said my system does not go to deafening levels.

My physical requirements are:
18" maximum height & width
24" maximum depth
Front firing driver

Not a requirement but natural cherry goes real well in my room (probably wouldn't go for black). The ASW750 does meet all the requirements but I haven't heard them, I'm also not stuck on B&W for subs so fire away (so to speak). Oh, and maximum budget for the pair would be $5000.

So any recommendations are very welcome and thanks for your ideas ...