Honestly i like the simple and intuitiv solution, but what makes me a bit worry is that you use MobileCoin for transaction solution as there are a lot of other and better solutions.

One look on Wiki. about MobileCoin made me a bit more sceptic about it as i am paranoid human and thinking that the tansaction data within and incl. the chat can be catched by the actors in the background which i personally don't support as they work together with other actors which i really don't like and in the name of humanity would never support.

Maybe i should give Radar and MobileCoin a chance. But atm as long as Radar works with centralized companys especially whith connection to DARPA i think that it is going to break the trust when time will come.