Confirmations > DSP + noRBF > RBF > LN
Agree nothing beats confirmations, nothing is final until it's on chain, but if you are going to go the non-final settlement route DSP + noRBF is definitely safer than RBF (much smaller chance) and better than LN (automatically confirms shortly after and doesn't have all the other problems adn complexity involved with LN).
Yes, I get what you mean by cash not being perfectly fungible. I think you are right. It is just a simple and easy to understand analogy because almost everyones accepts cash as the same without discriminating based off the ID number. You also cannot know the full history of a cash bill and everyone who it passed through. The same way many Bitcoiners use the digital gold analogy even though there are differences.
Yes, even Monero is a double edged sword. The problem I see is corrupt governments won't use Bitcoin since it is transparent and accountable. Just like they could be transparent and accountable right now and don't do that. We can't force them to use it.
They will demonize Bitcoin and Monero in the eyes of the public because they can't control it. But that is ok because we can use it and they can't stop us.