Hi @richard-rickett, I’ve moved your comment here because it’s a more relevant thread 
If it is possible to mix and match them it would almost certainly still be constrained to the performance of the slowest board - that’s pretty consistent across communication hardware and protocols.
As is discussed above, the higher end RAK boards (there’s also an LX200V50 now) may have better sustained performance at long ranges, but they can’t reduce bottlenecks that are caused by other parts of the system (e.g. a Raspberry Pi 3B only supports 100Mbit/s ethernet, which is also currently the case for our Ethernet Switch).
As we’re now moving to vehicles with an onboard Raspberry Pi 4B (which supports gigabit ethernet) we’re also looking into ways of improving networking bandwidth throughout the system, but we don’t have anything to announce on that front at this stage.
For your reference, these other posts may also be worth a look: