I dont get what the deal is with efficiancy, if you can play a game with it then its fine. You wont be carrying more paint than you can shoot with any marker.
Then you can fill up after the games. Its ez at training an takes like 2 seconds, the only time i can see having a more efficiant marker being a big deal is Xball when you simple dont have time to fill it up constantly, but how many events are there in the UK where you dont have time to fill up between games?!
Just get the shocker, get a decent bolt, it will be fine, if it aint broke dont fix it!