You weren't asking for opinions on the value of LTC insurance, so I'll keep it short. DW and I have been pitched a variety of LTC products over the years, including the lump sum type policy you mentioned. In the end, we decided to self-insure. Our reasons:
1) Experience collecting benefits from parent's LTC policy was a nightmare and once we were able to collect, the benefits still never came close to the total premiums paid over many years (i.e. our parent clearly would have been better off should self-insured).
2) The policies are expensive and premiums can escalate over time, which is why the lump sum policy was pitched to us by an advisor. But, there is no way I'm parting with $100K upfront to an insurance co. NO WAY.
3) The policies are impossible to understand and written in gibberish. Trust, I'm no stranger to complex legal documentation. If I can't read it and understand it, 99% of the population would not be able to either - and its clearly written that way to obscure important stuff, like how much you're being ripped off. If I need an expert to interpret what I'm buying, no thanks.
4) These policies can be bought, sold, and traded between insurance co's, which means you could start out with a decent, creditworthy, well-rated company but end up with a really crappy fly by night one.
That's my [reasonably well-informed] take.