There's not even evidence that high normal testosterone levels are healthy; for effects on overall health they are likely less healthy than normal levels. For men not on TRT, high-normal testosterone is more likely reflecting above-average SHBG. In these cases free testosterone is probably not high. In contrast, men on TRT may generally have average or lower SHBG, in which cases high total testosterone reflects high free testosterone. The free hormone levels are usually going to be more important than the total levels in governing long-term consequences....
Is there really any evidence to suggest that high normal E levels are any less healthy as high normal T levels?
In sum, we lack evidence on the long-term safety of either highish testosterone or highish estradiol. We can certainly point to common side effects, such as elevated hematocrit and water retention. These may simply be the most visible warnings against running hormone levels higher than is natural for the individual.
I believe there are some data pointing to problems in males when estradiol is relatively high compared to testosterone. I think one of the issues is harm to testicular tissue. It seems likely that an imbalance in the other direction is also not going to be healthy.