When the 800D series first came out, it had somewhat mixed reviews. Some didn't like it as well. The 2nd generation diamonds, such as 802D2 (branded as 802 Diamond), had significant improvements in the tweeter crossover as well as the tweeter motor. I know this turned out a lot better than the original "D" series. I wonder if you listened to those.
I have the 2nd generation 805 Diamond D and HTM2 Diamond center channel. These are just excellent sounding speakers to me.
Just another opinion. I have not heard the D3 series.