One thing that's really not been expanded on properly is the 4in1's support of "Spektrum" and "Futaba". Yes it does work with DSM and SFHSS, in the aircraft variants of these protocols. It can bind to DSM2 and DSMX receivers in all their variants and SFHSS air receivers. But check out Futabas compatibility matrix for SFHSS receiver support. Apparently the surface SFHSS receivers can bind to surface SFHSS transmitters, but not Air SFHSS transmitters. And Air SFHSS receivers can bind to both surface and air SFHSS Transmitters.

So at the moment there is probably more reverse engineering work for the multiprotocol team to do to get DSMR and surface SFHSS working.

The good news is on the Multiprotocol website it does say Traxxas support is there and working on the 6519 receiver, which seems like a common Traxxas receiver. So I think you could reasonably expect the radio to be able to bind with Traxxas RTRs.

At the moment though I doubt its going to bind to any existing Futaba SFHSS surface receivers or any Horizon hobby RTRs with the DSMR protocol. So that needs to be kept in mind for people considering one of these. Worth noting it does work with tons of other common protocols you could get dirt dirt cheap receivers for. Such as flysky's AFHDS2 and it's 10 dollar receivers.