Pretty cool, hope it keeps getting refined and eventually makes it into the Monero codebase so it can happen automatically for everyone with no additional cost or bloat.
Seems like a nice feature. I can't comment on the possible risks mentioned in the reddit post. I like your writing style. Good and interesting to follow.
The privacy concerns are valid and it is true that the chain would get a lot more traffic from this feature, it is probably alright for the people that right now are already fine with using transparent chains for payments. It's a mobile-hotwallet and while some people might have a threatmodel where losing some privacy is not acceptable, I personally would just use seperate wallets for different usecases. I'm also fine with having some more chainbloat if it means Monero becomes way nicer to use for the not-so-technical people and instead "it just works".
Honestly, I don't think the 20-minute "security" barrier is an barrier at all. You really think without more people would use it, why? If you understand or know why it's there, you can deal with it. And if you really need multiple transactions in a short time, then using multiple wallets or sending transactions to yourself between two wallets and different addresses seems like an acceptable sacrifice, like you have written. But still, if they improve it, all the better.
