There are plenty others offering north of 4%, and north of apple's rate, that are reputable (not saying UFB isn't, but it's definitely not a household name).

The delta between, say, 4.55% and 4.8%, on the amounts I'm holding, may not be worth the potential extra headache of working with a lesser known bank. Introducing more risk (or just taking time to open more accounts) to earn, say, an extra $8/month... at some point becomes not worth it.

Very true. It irks me that Chase/WF/etc offer 0.03% or something, what am I supposed to do with that rate, other than take all my money to some other bank?

It's a legitimate bank, but the banking experience feels very third rate, and online reviews are scathing. I opened an account but chickened out from depositing anything after their account linking didn't work and no support for that.