I'm owner of Pebble Watch. It has great built in app to control music player, it shows track name on watch and allows to control player (play/pause/next/previous).
It works great with Poweramp 2 but it can't control Poweramp 3 for some reason. It shows track name without any problem but play/pause/next/previous buttons not works.
It's weird because AFAIK it just simulates multimedia buttons. I can control any other music app using Pebble and can control Poweramp using any other device.
This is the only reason to go back to Poweramp 2.