Should also be noted SMS with or without RCS should still be considered a legacy communication method and only used where necessary. 

Legacy calls and texts should be avoided as they're not secure and trust the carrier / network along with having weak security against other parties.

Our recommendation is still to get as many of your contacts as possible to use Signal or other non-carrier-based communication apps using the signal protocol/secure E2EE encryption. It is why we don't give the stock AOSP Messeging app much attention to encourage people away from using it.