I was ATC for 12 years. Recently quit to come back to flying.

-ATC overtime is mandatory, 6 day work weeks and many facilities are actively doing this.
-Non-essentials (QA, QC, 2nd level managers, etc) don't come in during the shutdowns but still get back pay and accrued leave
-Essentials don't get anything extra for being essential however any leave they take during shut down doesn't charge their balance (free leave)
-For a lot of controllers this is the 4th shutdown they've worked through. Each one comes with idle threats from management and win one for the Gipper speeches from the union.

I wouldn't bank on the NAS running as smoothly as it has in the past. Staffing is thin, like really thin...and fool me thrice shame on you.