6600 firmware should be out within 2 weeks according to supplier.
PQ on 6600/6500 vs BDP will not be too much of a difference on lcd/plasma unless you are using FHD projector with FHD screen on a big screen.
AQ on media players vs BDP will be very obvious. I've compared the same movie on 6600/6500 vs Oppo83, the sound quality is totally different. bass is much tigher, details are better and more dynamic.
Of course, it depends on the Sound system you are running on. If using consumer brand HTiB, u might not notice much....but if u r using 10k above system, the difference will be a lot.
6600 vs 6500 ...6600 loads faster and GUI looks better than 6500. Feature wise, 6600 improved on the internet side and navigation and preview mode. according to dvico, all 6500 functionalities will be available in 6600 once the next firmware is released. so just sit tight and hopefully within 2 weeks time, 6600 users can enjoy the full functionalities.