Mayo vs. Cleveland Clinic?

After about 2 years of consulting with various specialists in my area and not seeing much improvement, my pulmonologist thinks I need to see “super specialists”, specifically recommending either the Mayo Clinic or the Cleveland Clinic. I was just wondering if anyone has had experiences with either clinic or has heard if one has a good track record of working with Long COVID patients (a few of the specialists I saw didn’t believe LC was real, recommended anti-depressants, etc.). My symptoms are primarily dyspnea and tachycardia on light and moderate exertion and PEM/chronic fatigue.