Hello,
No official tests have been performed on the matter.
However, the theoretical device limit is that any 1 node is limited or restricted to 32 "Neighbours".
You have to also be aware that in mesh configuration, each additional hop will introduce the loss of about half of the source throughput, resulting in exponential loss of speed as the number of nodes/hops increases. Depending on your case requirements, this should give a baseline of what to expect if the throughput is known at the mesh gateway.
Best regards,
