Aerial Model 9 vs B&W Nautilus 802

the 10t cost too much to build, so it was replaced by a more margin friendly 20.

I think the 10Ts weren't all that great to look at either. Notice how a lot of the high-speakers have gone to the faceted look, e.g., Andra's and others. I didn't ever care that much for the look of the 10Ts but they're growing on me. Of course the 20s have the more modern look.

The expensive part Jaybo refers to are the Novalith heads. Basically casted granite. They also have had some problems with the outer coat peeling off. Mine aren't showing any signs of that but I've seen quite a few that have. Not sure why some do and some don't though.

I've been told that the 9s don't hold a candle to the old 10Ts.

A little harsh. Aerial themselves don't share that opinion. You should listen for yourself. In the meantime, here is a quote from TAS reviewer, Jacob Heilbrunn:
"the multi-driver tower Model 9 represents a big advance over the venerable 10T, and I would rank it among the most enjoyable loudspeakers I’ve heard."

Has the 10T turned into a bit of an urban legend?

They were very popular and musical, so people remember them favorably. Sort of like the Mike Kelly designed ADS speakers I owned many years ago.

Aerial themselves commented that the Model 9 is their best seller and they are very pleased with their performance and have no plans to make any changes to them.

That is what I was told the last time I spoke with them.

After having owned them for several years, I can say that every improvement or change in amps, source, cables, etc. will be faithfully reproduced by the 9's. They are more user friendly than the 10's, with a sensitivity of 90dB at 2.83 Vrms and 1.0 meter on axis. I can drive them to high spl's and with tremendous dynamics using my 100wpc hybrid amplifiers. Soundstaging, detail, dynamics, and extension are all good to excellent for their class. They display richness, texture, and realism, when used with the right equipment. To me, they are very musical and grainless, and their greatest strength is the sum of their strengths across the board. The bass seems to be the main discussion point. The HT crowd cuts them off low and uses a high quality sub. Music lovers play them full range and enjoy bass to about 30 hz. They are bottom ported and must be positioned on their dedicated stands to sound their best. In smaller rooms, you would be better off with the 7b's or other speakers. The 9's need some room to breathe, a moderately large sized room, good power, and good cables if they are not to sound boomy. Aerial is a superior company to deal with if you ever need support. If you haven't guessed, I am a very satisfied customer.