The Elvis In Concert CD definitely has inferior sound to the others you named. The others have been released or upgraded more recently, but I think it is also an issue with the original recording and mixing. (The On Stage LP had a much cleaner sound than the EIC album, as a case in point.) And for whatever reason, the second LP / the second half of the CD is not as good as the first.
Hopefully FTD before too long will give this material the treatment it deserves.