I lost some money, or at least had a hard time using it, because I was quoted a price for something, set the FSA for the next year based on that, and then the billing ended up where only some of the price was eligible for FSA.

Combined with the PITA level, there's no way I'm doing it again. I can't see how it's worth my time. One of these three options is very likely:

a) my income level is low, so every dollar counts, but my marginal tax rate is also low, so spending a ton of extra time on this is not worth saving ~ 15% on taxes for health care

b) my income level is high, so my marginal tax rate is high, but saving 40% of taxes for health care is not worth the time, because health care is not a meaningful amount of income

c) my health care spending is high relative to income, and I can deduct health care costs on my tax return. Then I can deduct a lot more than the FSA will reimburse for, and the records don't need to satisfy a third party, unless I'm audited by the IRS.