B&W 800 Series D3 vs D4

Hi,  has anyone here heard or owned both D3 and the latest D4 version of B&W 800 series speakers?  I would love to hear your opinion comparing the 2 versions.   Is it better or worse in all frequency range (high, mid, & bass)?  and is it worth the money to move up from last gen D3 to the current D4?

I currently own a pair of B&W 804 D3, and have been thinking about replacing it with the 803 D4.  So far I'm pretty happy with the 804 D3.  I only wish it has more slam in the bass area.  Also, I don't listen to music very loud anymore.  I have some hearing loss and tinnitus, and loud sound always elevates my tinnitus, so I'm careful with the volume these days,

Anyway,  love to hear your experience if you have heard both D3 and D4. 

Thanks very much!