What you are saying I need is what I have but its by a different manufacturer. I have the slide fire recoil "enhancer". I have to disagree with you. I have been shooting my slide fire for years and its easy to get a fast fire rate with a 25 round mag. The extra weight of the 50 round mag is taxing on the recoil of a .22lr. If you notice in your video even one of the clips they use has a huge lapse of time between round 1 and 2 as the gun barely had enough recoil to fire the second round on a full mag.
Now yes I agree it has a faster fire rate but it has a lot to do with the weight of the gun. Ill prove this next time I can fire my gun with the 25 round mag. Its simple physics less weight means more recoil and faster fire rate.
As for the 3.5lb trigger I also have to disagree just watch this video with a 50 round drum and a JARED 1.5lb trigger. The fire rate is plenty up there with out the recoil "enhancer" you mention but with a simple addition of a lighter trigger.
All of this will be covered in my mag review....