Dynaudio vs B&W help...

The Dynaudio speakers have a midrange bloom type of sound.  The midrange is very full and strong and forward and lively (probably more forward towards the upper mids).  This type of character extends into the tweeter area as well.  The tube-like bloom is not very accurate, but it is loud, exciting and lively.  Very strong and forward presentation.

The B&W D2 series have very clear and accurate highs, due to the diamond tweeter.  The bass is good and tight.  Mids are somewhat soft/warm and a touch laid back (due to the Kevlar driver), but they are very natural sounding.  It represents how a voice sound "naturally" much better.  Overall, I think the B&W is a more accurate and natural sounding speaker, but not as lively/strong as the Dynaudio.

You are right, the "new" Dynaudios have been voice much closer to neutral (no longer have a "bloom").  They are smoother and much more controlled.  However, I don't know that I fully agree that the tweeters are better than B&W.  The new Dynaudio tweeters are very clear and clean.  (The Op was asking about the Focus 600XD, which is the old Dynaudio sonic signature).

The B&W Diamond tweeters have a "bite" to the sound that kind of reaches out and grabs you.  The "new" Dynaudio has a clearer and more solid sounding midrange than the B&W D2.

In my opinion, the B&W would have a much more exciting sound for HT, and I think it still sounds more "natural" than the new Dynaudio..  The "new" Dynaudio has a much more controlled and linear response, probably leaning more towards the Sonus Faber type of sound.

I think it depends on your tastes and what type of sound you're looking for.

I think your AVR would be fine.  It is 170 watts per channel into 8 ohms, or 270 watts into 4 ohms WHEN ONLY 2 SPEAKERS ARE DRIVEN.  Or it is 120 watts per channel when all 7 speakers are driven.  This is still a good size shared power supply.  You are never going to use all power for all speakers concurrently.

The 804 is considered an 8 ohm speaker, but the impedance will drop down to 3 ohms (not entire sure where).  I think you may start having challenges with an amplifier that is 100 watts or less, but it still would work.  With your specific AVR, I think you are fine.  If you really wanted to, you could always attach an external amplifier using the Left/Right Pre Outs.

@toddcowles - The B&W D2 is going to be a slightly warm/soft response in the midrange because of the Kevlar.  The B&K 200.7 is an great amp with high current, but it is extremely warm sounding (I had this exact amp in the past).  I can totally see where the combination of these two items would sound very lackluster.  The McIntosh would probably do better, but still the McIntosh is not a very fast amplifier - McIntosh will lean toward a full and warm midrange (but probably not as extreme as B&K).  The D2 series would do much better with amps such as Krell, Classe (new stuff), or Bryston or Plinius.

The B&W D2 series really needs a high current amp with very fast resolution.  The Cambridge CXR 200 should be just fine as the Cambridge has a faster and more dynamic sonic signature.