The buddha rope is mainly for left (or fingering) hand strength and speed.
For the fretting hand, the key is to minimize the movement. Make every pluck short and focused and move both fingers simultaneously, i.e. while plucking, move the other finger so it's ready for the next pluck when the first is done. Check out the exercise sticky here as well. Lot's of good exercises there.
I've never become fluent on using 3 fingers (4 is out of question before I master 3), but I'd love to become better at it so I'm practicing it every once in a while. I believe you can gain a lot of speed by simply using one finger more. It's just a matter of practice, me thinks...
Good luck!
Good luck