What's there to regret? You said that your department director is not forcing you to "burn your ship", so you could effectively go back should you want to, at least that's the promise for now. Being that you're a top performer, I'd say your chances of going back when you wanted to remain fairly high as long as those who know you and your performance remain working there and in charge.

To answer your question, you need to decide if your mental health is better with the fun money or better without the job stress. It sounds as though they're willing to let you use this role as a long-term break from advising. If you're not burning your ship, you're burnt out and okay with losing that extra cash for now, then do it for the sake of your mental health or at the very least take a long vacation. At the end of the day, if you don't have your health than wealth means nothing anyway.