The SLX will suit your Redington CPS just fine, the #6 line was developed and tested predominantly on a Helios 906 tip flex which has a very similar stiffness & action to the Redington. I like it for general fishing between about 20' & 70' with dries, nymphs & anything else that you may want to throw at a trout. With the right leader set up it will carry just about anything and present it well.
Cheers
Ben