I've been running through this for DW and her DM. Their lump sum only buys about 75% of the monthly income when purchasing an annuity elsewhere. Could be because she's female but pooled with a bunch of males at work. The interest rates assumed by the lump sum calculation seemed pretty reasonable, and government mandated. But if you make optimistic market assumptions the Lump sum could be much better.
Given two SS incomes, I'd be willing to go lump sum, especially when the pension is not COLA'd. The lump sum would go into an IRA. It would increase RMD income, but not as much as taking the monthly pension at age 70. So we'd have a little more control over our income. And the kids could inherit any remainder. It eliminates one more set of paperwork/EFT's. No concerns over pension funding (though it must be better than 80% funded to offer lump sums). We could Roth convert it if that look beneficial, so more tax flexibility. And we weren't planning to start the pension for another 10 years, so we have some time to smooth out any market dips that might be coming.
DMIL already falls into the the other risk of lump sums, wanting to spend it now. At least for her it's a small part of her income, one she found out about only a couple of years ago. So while the income was nice, it won't be a disaster if she takes a lump sum and spends it.
No decision yet, we're still discussing and waiting to see if we think of anything else.
