B&W 803D2 for $4,500?

+1 for 803D2. I have owned both 803s and 804s, you will appreciate the improved crossover, better low end along with crisp top range due to diamond tweeter. 

Thanks for the suggestions.  I'm leaning towards buying them simply because it's such a good deal and, if I hate the combination with the HTM3s, I could easily resell them for more than I paid for them. The speakers are local and close to my house, so it's an easy pickup. Doesn't seem to be much downside.

Yes no doubt

Win200- 

No doubt that the 803D2s are nice speakers and the price seems reasonable, but if I were in your situation, I think I might apply that same $4,500 for an original pair of N802s instead which should be doable at that price (or close).  Since the N802's also don't have diamond tweeters as your existing speakers, I would put the 802s up front, leave the center alone and use your 804s for your surrounds.

Only hesitation I would have in this recommendation is if you don't have the amps to power it all.

All that said, to answer your very specific question, I think that match would be OK, but the center might sound a little dull compared to the D2s but EQ/gain on that channel should be able to balance it out assuming your processor has that ability.

Greg