Can you actually fund a non-employer HSA with tax-deductible funds, or is that a benefit that only applies to payroll HSA contributions? If not, a lot of the benefit of an employer HSA disappears.
(FWIW, I have an HDHP, employer HSA, and an individual HSA that I roll my employer funds to annually for lower-fee investing.)
Only partially. If you fund your HSA outside of your company's payroll system you can deduct your contribution amount from your MAGI for income tax purposes, but you still have to pay FICA taxes (social security and medicare) on that income.
If you have your HSA contributions made through your company's payroll department, then you don't have to pay FICA taxes on it.
HSA Authority (part of Old National Bank). Last time I ran the numbers, the break-even point on annual expenses vs some other options was about $10k in HSA balance — where smaller balances would pay more at HSAA than some other provider(s). But they cost less than other providers for larger balances (again, last time I checked).
(FWIW, I have an HDHP, employer HSA, and an individual HSA that I roll my employer funds to annually for lower-fee investing.)