When I think of ERing, I am haunted by dear departed grandfathers and uncles saying "you don't just walk away from a good job like that!".
In addition to my main reason of not ERing yet, your reason is another slight additional factor....I mentioned to my father last week of what I could pull from my portfolio for the rest of my life (adjusting for inflation), and he just simply said "but what about continuing to do something with your life and make more money?" With him, it's part 'hoarding money/trying to accumulate as much as possible', and part 'not having much passion for anything but his job' and spending time at their place in Florida (which is sad...but if that's what floats his boat, then so be it)
A big thing that holds me back from retiring is the political unpredictability of the weasels in our state government. Teachers have been made out to be Public Enemy #1 in Michigan, and are taking the brunt of the "reforms" handed down from Lansing. I fear retirement because it has now been shown that the retirement benefits my DW earned and been promised over 30 years can be changed or eliminated on the whims of a bunch of clowns who wouldn't last 30 minutes in a classroom, let alone 30 years. Other reasons: what will Social Security look like in 9 years; when will the stock market take its next big drop; what will health care be like in a few years; can I trust my megacorp to pay me my pension as promised for the rest of my life?
Sorry to hear about the vagaries of the legislature regarding unpredictability of your DW's pension!
Has there been any legislation so far (either simply proposed or even passed) which would give you a hint as to what the effect might be to form a "worst-case", "probable case" and "best case" scenario? If so, run those numbers and see where the dust settles. I have no knowledge of this issue in MI, but, can you reasonably say that at least half of DW's pension amount is safe? There's no way they would completely eliminate it to zero. How would that come out in the numbers, adding in SS, your portfolio, etc.
Is it possible for DW to get a job in private industry, even though she loves her position, or does her 30 year tenure give her a good position that would be tough to match (ignoring her pension which she qualifies for now, but which might not give her much more benefit if she stays in). A higher salary for DW in private/other settings might help boost the portfolio a bit more and let both of you RE sooner rather than hinging on the uncertainty of pension changes.
Regarding SS - pretty much everyone is confident that given your current age, SS benefits likely won't change. The only possible 'gotcha' may be that they become 100% taxable instead of up to 85% taxable, so perhaps try factoring that into your forecasting and see.
Does your employer offer you the option of taking a cash balance transfer out, or are you stuck with the pension?
) I know how you feel. It's a zillion of "what if" before you can pull the trigger and eventhough I am not there but I am sure it's pretty scary decision.
This forum really pushed me into getting my ducks in a row, and I thought I might pull the pin this spring, but when push came to shove.....well, you know. 
I just got a 38% bonus - it's tempting see if I get another in OMY even though I most likely don't need it ! My 57 year old body says to stop the over - W*RK, and enjoy the fruits of labor. 
