The Adams 6th partial is the best I personally have played, and since I do own on older sovereign I know the pain of this. At worst F is still around5-10 cents sharp(varies with your setup) but is easily lippable. For me C5(piano reference) for me is generally flat with 1st valve so depending on the day I'll use open to play C, but other than that there isn't anything major(may be due to lack of strength in my high register). Top space G is anywhere from 15-20 cents sharp, or in tune with 3rd valve in place of 1-2. My second Eb in the staff tends to be around 5-10 cents flat when all my other notes are in tune, again easily lippable. Overall it's a great horn, fits me really well. The tone is gorgeous, even in comparison to the old Bessons.
As far as bell material I couldn't tell you how much of a difference it will make, I don't have enough experience in testing the different materials and it changes with brands as well. I'll let someone else give comments on that section!
Adams E1 SS, Gold Brass Body .6mm DE Euph N103 Jcup, J9 shank
Meinl Weston 2141 Eb Tuba PT 84