With thryoid and testosterone, my opinion is that the healthiest levels are the ones where you feel best at. Feeling good, or at least better, is your bodies way of telling you that this is where you should be. So in your case, I'd go w/ the hyper side of things.
I believe it's safe to stay in a mild hyper state. As long as you not having any bad issues, not sleeping, losing too much weight and high blood pressure. It seems when I'm in a mild hyperthyroidism, I sleep better, my blood pressure is better and I just feel better. Oops can't forget about my good LDL cholesterol.
