My opinion, I don't think you should roll it over to an IRA. From what I can tell from your post, the cash-out value is going down, but your defined benefit is not.
Those monthly payments (if you took them today), are the equivalent of withdrawing 6.6% annually. Unless you have health problems, keeping it there and starting withdrawals in 2023 sounds like a pretty good idea (equivalent of 12.3% annual withdrawal). If you were taking 12% out of your IRA, there's a good chance you would run out of money at some point, right?
To me, this decision would be based more on how long I think I might live, the health of my spouse, and how important it is to leave funds for my children.