This seems like a no brainer, but let me run this by you:
Previously my employer had my HSA in Health Equity, which is a terrible HSA provider so I switched it to Health Savings Administrators (total fees per year are >$50), which allows my to invest in VTSAX.
However, my employer switched to Fidelity, and the employer covers all of the HSA maintenance fees. Thus, I can switch my money into the Fidelity VTSAX equivalent for free.
So, my plan is to switch it all; I'm not missing something, am I?