Yes, WHV has usually delivered excellent transfers of their catalog titles whereas their new releases on DVD started to look atrocious circa 2004 (plenty of compression artifacts and ghosting).
TCM is part of the Warner Brothers family after WB bought the Turner library and you usually start seeing certain films in very good condition just prior to their DVD or Blu-ray release. Not just films from WB but from Criterion, Kino and others. A few weeks back, I caught a bit of Buster Keaton's short ONE WEEK (1920) on TCM-HD when it was being aired prior to a feature film - it looked phenomenal and I wondered if there was going to be a Blu-ray of it soon. Then, a week or two later, Kino announced a Blu-ray release of Keaton shorts coming out this summer.
Now while I don't have confirmation of this, I was under the impression that a 4K scan was completed on AMBERSONS two or three years ago, so TCM should be showing a better quality version by now. Perhaps WHV has held back on releasing the new master to TCM to make it a bigger DVD release event (yep, that was sort of a joke). Then again, AMBERSONS was screened as part of TCM's first Classic Movies Festival last year in Hollywood - logically, that would have been the time to unveil a new and improved version. Has anyone heard anything about that screening? I agree that "Digitally Remastered" implies that some kind of work has been done, but that term has been around for a decade; a 4K scan would warrant the claim "Remastered in HD" which we're not hearing. If this was a proper catalog release (even if just on DVD), I'd feel certain the quality would be top-notch. But throwing it out there as an Amazon.com exclusive bonus feature to KANE makes me wonder.
By the way, I have yet to be alerted by Amazon that AMBERSONS is coming out on DVD even though I signed up to be pre-notified eleven years ago!