I didn't want to get sucked into another chain vs. belt debate, but:
-Belts are lighter than chains. But, Vexpro pulleys are not lighter than sprockets. A 15mm belt drivetrain weighs as much as a #25 chain drivetrain, generally speaking.
-Belts are quieter than chains, and more efficient. However, 234's paper only covers #25 chain and not #25, and used an 8020 chassis to do it, so the exact amount imo is unknown.
-When put together with a Dark Soul tool (for #25), chain is extremely strong. Plus, masterlinks are at least $1 per chain run.
-Chain can be assembled on the sprockets, while belt needs pulley removal to go on if you're not tensioning.
-Belts will slip before breaking gears (on arms and stuff, anyway) depending on tension, whereas chain will kill everything before it dies in a spectacular fashion (ask me how I know).
That's all I think I know right now.
I like belts everywhere but the drivetrain, personally, but they require forethought.