OP…”do the woofers on your 800 move noticeably under load? Mine barely move while my subs are going nuts. I’m not expecting the same level of excursion on the 800, but more than nothing. ”
I have been scratching my head at your problem. B&W tend to be bass heavy. When I read the above, it makes me think you are not going for accurate sound reproduction… or even close. I’m not being critical, different people want different things. I used to have dual B&W 800 series subs with my system, in a large room. They had to be turned down below 10% or they would screw up the imaging and sonics. I could never see them moving. Having subs going crazy might be true in a home theater playing U-571 with the depth charges going off but not in a two channel audio system playing music.
It sounds like this version of speakers may simply be more accurate and thusly less bassy. they are up a tier from your old speakers. It sounds like the version of music you want may require equalization to give you the accentuated bass you are looking for.