OK, they just have a different set of Admiral Share funds than HSA Administrators. Both HSA Administrations and Optum Bank have Wellington but then different types of Admiral funds as well as funds from other institutions.
Optum doesn't have an international fund it appears.
Here is their fee schedule:
HSA Fees - OptumBank.com
So $3 a month if you keep less than $5000 in a bank account. Your investment balance does NOT count towards that balance threshold.
So in effect, if you just contribute and maintain HSAs there, it's $36 a year vs. $45 at HSA Administrators.
I don't know if the various withdraw options are cheaper at one institution or another. Seems like they charge for ACH and checks and $2.50 for ATM transactions. Seems like it would add up, though I would do minimal withdrawals for awhile.
I thought about moving my HSA before the HSA Administrators changing their website again in September but since I've paid my annual fees, I might as well wait, instead of transferring now and paying Optum $3 a month. I don't see the point in maintaining a separate $5000 bank account in addition to an HSA with Optum to avoid the maintenance fee.