Depends on what you want. I have the cal, scal, and ckye. I'm going to sell the cal because it fills a similar role to the scal, just smaller and lighter. I love the flexibility of the ckye. I really like the scal from a bench type setting though. Rock solid and has very little play.
I have 0 time in PRS but I have ran the ckye in 3gun. Even with the pic rail, you can still quickly adjust position due to the design.