6T drivers are shown in more detail here:
https://www.remusic.it/EN/Aerial-Acoustics-6T-loudspeakers-81b35000. It appears that the woofers and midrange are SB Acoustics given the papyrus blend. The tweeter is the Scanspeak Discovery tweeter (not the Revelator as incorrectly stated at the above link). All are customized to some extent for Aerial by the respective manufacturers, but agreed that they are pretty cheap drivers considering the retail price of the speaker. The stock version of the tweeter is available from Madisound for $54 (non-volume pricing of course).
The 6T was in the top 5 or so speakers I’ve heard, though I preferred the 7T to it. Recently, I heard a pair of 6T driven by a Naim integrated amp at a friend’s house and they sounded horrible. Narrow staging, rolled off treble, and weak bass. Very much outclassed by a pair of KEF floorstanders in that room and on that same amp. At the dealer’s, my impressions were basically swapped between Aerial and a different KEF floorstander. Would not recommend buying unless you can try in your own room on your own electronics, especially given the comparatively poor (and continuing to decline) resale value of Aerials due to a particularly vocal disgruntled former dealer.