It sounds like you're in great shape either way you go, so congrats on that.
I had a similar decision to make recently, and even though I was within the limits of the PBGC backstop, I ended up taking the lump sum. I'm still not positive I made the right decision. Something about a monthly paycheck is quite attractive.
By the way, I worked for a company that went through bankruptcy after an ugly debt-financed takeover, so it made me sensitive to what the PBGC limits are.
Fortunately, DW and I are also in pretty good financial shape, so the decision is likely to have a greater effect on our heirs.
One more thing: I really liked my job, but retirement is great!