For perspective, I have Rio Gold in my Winston BIIX and wouldn't think of going with Grand on that one. Although it's rated as "fast action", compared to "fast action" from Sage, that rod is really medium. On my Z, I prefer the Grand as mentioned it's 1/2 size heavier and loads the rod nicely for me. You should find out what kind of action the Loop has and make your choice on that or you may find that you're buying new line for it.

From Leland's website the description of the rod is:


The Loop Evotec Single Hand 9ft 6wt Fly Rod, 690-3A MF has the backbone for going up against large contenders, yet it still maintains a high level of stealth. With its medium fast action, the Loop Evotec Single Hand 9ft 6wt Fly Rod, 690-3A MF is easy to cast and has enough length for creative mending.

I'm not familiar enough with Loop Rods to compare their medium fast action to that of Sage or Winston. I might start with Gold based on this, but this is just my 2 cents.