So today I drug out my old faithful, Susan Bates #11 at 1.15 mm and put both hooks together. Well, no wonder I'm having tension problems.
Look at the difference in head sizes. More importantly, look at the difference in shank sizes where I generally work my loops. When I went back to 11/0 and 10/0 beads my tension was way looser than I wanted it to be. When I swapped back to the Susan Bates hook, all the tension problems went away.
So, I guess I should have taken my own advice. Or at least I should have taken a good look at the hook differences some time ago. These Profi hooks have been discontinued, but I did manage to find one that is more the same size as my Susan Bates.