I've been pulling around 4% out of mine for 7-8 years now as well as two lumps sum withdrawals ($50k & $100K) and due to market performance we have considerably more than what we started with. Just about to turn 67, might bump up to 6% or so in the not too distant future.
The big "what ifs" are the inflation rate and market performance. Since nobody has a crystal ball past history is all we have to go on.
The fact that you are even thinking about this puts you miles ahead of the average American. You're probably going to be okay.
