B&W Nautilus 802 compared to 804

Hmm...I too would consider the 803s IF you can sit far enough back from them to get good coherence. I couldn't.
Frankly, I'd swap out the 804s for the Revel Performa F30 if nearfield listening is required. Otherwise get the 803 and forget adding the sub. The 803 produces PRODIGIOUS bass, and has a far better balanced frequency response in most rooms than the 804's anemic bottom end.

I recently listened to the proAc .5. It at least approached the open, clear , sound of the 804's with bass. Ribbon tweeter, 3 way design. Only needs 100-150 watts so NuVista is overkill. For 6K this speaker was the way to go for smaller room without big $$ on amplification

I think 801 and 802 are very different from the rest of the matrix line. Get the 802 if you can afford it. The sensitivity should be very similar to the 804.

If I had to choose, I rather get an 805 than an 804.