For me the main problem with 0AD multiplayer is that if any player loses their connection even for a moment for any reason, the game either halts completely or forks so that they can't rejoin. Quite frustrating, especially for longer campaigns. It's also impossible to save and restore in multiplayer.

It did save in a27 for me - I had the same forking problem but was able to go back to a previous save and the other player was able to rejoin at that point. This was in a local network game.

This is one of the problems that BAR solves beautifully - a player could leave and rejoin later and the game would continue running just fine. An existing player can choose to take their stuff or not, or take it and give it back when the player rejoins. Truly elegant.