A lot of electro guns are adjustable from semi - burst - FA, and allow you to select any speed from 5 BPS to upwards of 15 BPS.
If you are getting an electro, it will probably include FA, and will fire faster than paintballs can feed. I don't need to go FA in order to get kills, I can't really afford to anyway.
It's a feature that you won't use all that much, and chops paint if you aren't careful. It would be nice to have though. I just wouldn't pay extra for the feature. I don't think most people use it too much, if at all. I don't think it can be abused. Some schmuck isn't going to be made into a better player because he is remodeling everyones bunker with a $1000 paintbrush. Good players use semi's, know how to move, and are good shots.
If I need serious firepower, I can semi fire 6-8 BPS out of a Tippman 98c with a 14" Lapco Bigshot barrel, otherwise stock, and I get best results when I double or triple tap the trigger. I am not an expert, but I have gotten lots of experts out! I need to go more often!