Every article and reviewer claimed the High Frequency driver was OK, mediocre, at best and needed an upgrade, and most alluded to the price drop as the result.
Be mindful that ATC did a serious upgrade of the tweeter several years ago that, from the reviews I read, was a significant improvement. If you’re reading reviews of models with the old tweeter you’re not getting an accurate assessment of how the speaker sounds now. This will obviously also be highly dependent on the electronics preceding the speakers, especially with very neutral speakers like the SCM40s, and with the refinement of your amp I’d tend to doubt you’d have an issue with the tweeter. That said, I’d also mention that both Music Direct and Sound Approach offer free shipping and a return policy where if you just don’t like the sound of something you can return it. You’ll be responsible for return shipping, but it’s still nice to have the option. Last, I highly doubt a tweeter results in a $2k price drop and think there’s gotta be something else at work there, but what do I know? FWIW