Now this may not be a fair comparison but since my dealer so eloquently claimed that new 802D3 rivaled the performance of 800D2. Well not to my ears, 800D2 was bit more transparent and offered much tighter bass. The mid-range on both speakers were equally good.
I still own a pair of 803s. IMO, B&W made biggest improvements from Nautilus to S series and then to Diamond D1 & D2's.
If money is no object by all means grab the D3. Otherwise, any used D2 series speakers are easily the best bargains in already over crowded world of high end speakers.