Re: Rio Gold or Grand for Redington CPX 4wt
Not a very accurate comparison as it's on a 10 footer but I put the Rio Gold on my 4wt Helios in tip flex and really like it. I just got another off ebay as I cut the previous one somehow. Some of the 2012 lines are $25 off as a shop in Chicago is clearing them out for the new 2013 lines. I think it's a good match as it doesn't feel like overkill with a full over-lining. I also think the road loads pretty quickly with minimal line out and I can roll over a pretty stout nymph rig with it. I use it for both nymphing and dries. Haven't tried the Grand yet.
I imagine your using the shorter 8'6" for mostly dries though so hopefully someone can chime in with a better comparison to the CPX.