I have not sold one either but understand their place.I personally have never sold one that applied a surrender charge on a lump sum death claim, but I can definitely see why carriers would have to do that & why a client might consider buying one with it because of the difference in interest rates, etc.
Some states, like FL, require a waiver on DB lump sum settlements so the "buy the rate down to get more features" products automatically come with that waiver.