Re: Line for Scott Radian
I have to speculate here but as you know, I tend toward extended head, long rear taper designs. SA Textured Trout(stalker) if you can handle the hiss, Mastery Expert Distance if you want quite, RIO Gold could be great too, you could try Cortland Boss as I have but I am considering cutting off the "high floating tip" which is softer than the line and causes line-to-leader energy transfer issues (in my opinion).
I had and experience with a 9'/#"4" S3 which at home just did not feel like when I tested it at a show. I called my bud at Scott and he said, "Oh, I forgot to tell you that the development line for that rod was SA GPX". I put a #4 (4.6) GPX on it and, low and behold, it cast fine. I don't happen to care for the blunt, hingey traits of that line's taper but it works on that rod. I only fish it in Colorado, which is not that often and I should punish it further by getting a Ross reel for it...I think I will. I expect Radian to be better about line tuning but it is worth a call to Scott Fly Rods to get their guidance. Please let us know what you learn.