Hi Matt,
Good to know that you investigating future options. Having a good solid communications protocol (MAVlink) is going to accelerate developments for all communities of UAVs.
As you probably know the UDB4 prototypes version 2 are in the process of being produced by Sparkfun.
I was not able to attend (or watch completely) Robert Navoni's in depth lecture on the Multipilot32. Sound interesting.
Best wishes, Pete