You really have to look at the value of ALL of the benefits. I'm not intimately familiar with NYC packages, but typically civil servants get platinum-plated benefits to make up for the lower salaries. Guaranteed low-hour work week, paid overtime or comp time, 11 paid holidays, pensions, free healthcare with no deductibles and great copays, and best of all you get both 401k and 457 tax deferred savings plans. Your calculation really has to consider the value of every benefit you get, then consider the lifestyle changes. Probably lower hours and all holidays off, more vacation, etc.
As far as failing pensions go, 401k's replacing defined benefit plans largely fixes the problem. NYC did that years ago. But even for cities that still have defined benefit plans, what happens in public service is that newer employees get the shaft, and they give great benefits to the older generations. Then the city raises taxes to cover whatever shortfalls there are. This goes on for years and years until the pension fails. If this becomes unsustainable (see: Detroit) the city just cries to the feds and gets a bailout, while the taxpayer funded handouts get cut back to egregiously generous rather than absurdly ridiculously generous. Then they post news stories about how pensioners got these huge cuts to their plans, which actually work out to something like reducing the COLA increases to match inflation.
So whatever plan you get when you sign up, you can pretty much count on that being available for you forever.