I'm not eager (in the 15% bracket next year) to move up to $11K out of savings and into a TIRA next year, but if needed to get our MAGI below 300% of the FPL, it's nice to have that arrow in the quiver held in reserve.
The general rule for any type of IRA contribution is that you must have earned income equal to or exceeding the amount of your IRA contribution. I just wanted to clarify that IRA Contributions can only be offset with earned income and not out of savings. HSA Contributions can come from either savings or earned income. This is how I understand the rules.