How feasible would it be to run a Bukkit/Spigot/whatever server and sync it with a PocketMine server? Ideally, players would be able to interact (see and chat) with each other even if they're on different servers, and the world map would sync as well, so structures and terrain would be the same and update when changes are made.
I know this would require custom plugins. Assume the servers are either on the same machine or the machines have a high-speed connection to each other. I want to know if there are any technical issues with doing this type of setup.
The only big problem I can think of is differences in available items, but that can be worked around by only allowing items/blocks present in both versions of the game.