There does seem to be a certain amount of richness lacking on those recordings. Thinking about the way In The Ghetto sounds on E1 though, that has to be just about perfect.
It must be those original mixes. Haven't played the 60s set in a while but I have had the FEIM extended CD in the car lately and it seems to me that the same thinness you speak of can be heard on that disc as well.
It doesn't help that on a lot of those tracks he was rather hoarse -- think Wearin' That Loved On Look -- and when you couple that thin sound with the extra reverb applied to try to mask the raspiness, it is less than ideal.
On Stranger In My Own Hometown, it sounds like he's singing into a tube or something.
Gentle On My Mind...no gripes there. Love that recording, and I agree with you about the Memphis record. The treatment of that song on that record I did not care for. I haven't played it in years though; maybe I should give it another try.
I can't vote right now. I have commitment issues.