I have not used them. I am very interested in them.
Rabotnik used them on his last EMC engine and said they worked very well. He said he ran them up to 6700 rpm with no issues. I don't know for sure, but I believe his were from Compcams as opposed to Scorpion. I don't think Compcams offers a short-travel hydraulic roller lifter to the public yet.
Just FYI,
paulie