Once you get the feel of the trigger pull, you should be able to consistently get 6 - 8 bps with the single trigger. The RT on-off will lighten the pull from about 8 lbs to about 4 lbs. Shimming the side of the trigger will make it feel more crisp as well.
I used an original metal mag single trigger frame for years with my Automag68. I got used to laying my index finger along the body and pulling the trigger with my middle finger. I found that it helped my pointing speed for accurate snap shooting and I could maintain pretty good trigger speed when needed.
Except for the Automag in front, its usually the man behind the equipment that counts.