Is "over cooked" a problem for you sound wise?
Yes it sure is in terms of listening level. I cannot crank it when it is "over cooked"...it just sounds harsh to the ears. At lower volume levels "over cooked" just sounds edgy or snappy, which is what the mastering engineers intended. So I can listen and enjoy...just like in a car or on PC speakers....at modest but not at anywhere realistic levels. I don't think this at all a problem to ATC...most anything that can play loud will show up this distortion and overly high average sound level problem. Remember at low levels the compression actually helps increase the audibility of the music - radio stations have been doing this forever - they want you to hear it...ever notice how loud commercials sound on TV - same thing!
Btw- your speakers Use SEAS cones My horns use SEAS also. They are really good cones.
Actually my old ATC's use the old tried and true Vifa silk tweeter D27-TG-46-06(nothing especially amazing at all but I like the sound) ...these are polite and critically do not compress/distort at high levels.....besides they don't do much work anyway since the crossover is at 3.5 KHz.
The newer ATC models indeed use the more expensive and highly reputed Seas T25CF-002 Millenium tweeters (as you say excellent drivers). The woofers and midrange dome are all built by ATC themselves and many of these drivers can be bought separately...see Solen Website and click on ATC.