Re: FERS annuity vs none?
If this were your final job, you might want to consider it -- if you leave Federal employment and take an immediate pension (for example, at age 62 with at least 5 years credit), then you can continue your health insurance (for which the govt picks up about 70%).* Of course, you'd be a fool to take a job you didn't like for 5 years just to get these benefits.* The 5% isn't much -- if you made $100K, that's only $5000/year.* $100K is GS-14-ish -- a fairly high civil service rank -- unless you are a highly desirably professional, it's hard to walk into these jobs from outside.
If you work 5 years now for the Feds, then 15 years someplace else (say), you are not eligible to get health insurance when you get your pension, AND your pension will be based on your salary when you were a Fed with no adjustment for intervening inflation.* That is probably not worth much.* And who knows when the Congress will decide to change the pension system again -- they keep making noises about it, but it will probably take a few more years before anything much happens.* And whatever happens will not likely be to the greater benefit of the employees -- there is talk of increasing health insurance payments that retirees must make, of reducing pensions, etc.