Welcome byage55 -- I also planned on getting out of megacorp at age 55 - w/ all the bennies. But woke up and realized that my job had become toxic for me, w/ all the travel, mind numbing conference calls and meetings, more and more responsibility(read even more travel and more meetings!)
I crunched numbers and found I could jump - at 49. Hey, if you like your work stay at it...I certainly could have retired in a more "cushy" manner had I stayed on til 55. I am afraid that I might not have made it....who knows?
Ya gotta do whats right for you. You have found the right forum, you will get all "angles" concerning ER here.