Agreed, if you have an HSA available it is probably the second places I would maximize contributions to, after a 401k/403b.

HSA contributions are arguably better considering they are not subject to FICA.

Yes, but only if they are deducted from your payroll by your employer, which is usually the situation when you have an HSA, but not always. You won't get a FICA refund if you contribute yourself off-payroll, but you will get an income tax refund at least.

As with all trustee-run plans, people should evaluate the investment options before moving the money in. The HSA I personally have access to is great for saving taxes on expenses, but if I wanted to use the investment options rather than sit in cash, my only options are high-fee managed funds (there's a lot less pressure on these vendors than on 401k trustees due to less public awareness)

Like an IRA, you're free to open an HSA with another provider and transfer the balance. You get the deduction from your employer and can invest in lower-fee funds. The best options are still relatively expensive compared to the IRA/401(k) scene, unfortunately.

It's like a traditional IRA, but the age for penalty-free non-healthcare withdrawals is higher (65 vs 59.5). Just something to keep in mind if you're older and think you might need the money sooner.

There is theoretically no time limit on taking withdrawals for medical expenses, so if you have enough medical expenses before you retire you can pay them with taxable money and withdraw in retirement those payments(save the receipts in case you get audited!). I wouldn't rely on that though, I'm sure the IRS will crack down on that if it becomes popular.

I don't see how the IRS would crack down on that unless the rules change. I don't see the rules changing without notice (time for people doing this to self-reimburse medical expenses before the rules change).