I have that rod FISHBOY1 and its 6 weight little bro. ton the advice of Airflo them selves I use the Airflo 40+ trout lines on the both of them.The 7 weight rods gets the 8 weight 40+ line.
I have to say they're a perfect match and will let you Overhead cast or Spey cast as far as you might want to with an 11ft 3ins switch rod!.
I tend to use both my rods with tapered leaders and tippet of 16ft in total length.They give great presentation and cast excellently for a long way!.
On the odd occasion I need to get down in the water a bit I use Trout Polys., but I've a stronger switch rod for the heavier duty fishing I need to do.
The Airflo NanTecs are excellent where presentation in low water are called for and really excellent at putting fish on the bank that could well shy away from a heavier presentation!.Don't be concerned at the apparent strength/power in the rods, I've had several fish approaching 18lb on my 6 weight rod and it coped really well.
This raises that confusing point about trout ratings and salmon ratings. As Rennie has just said that Airflo rod is trout rated (I have one too). As I recall the Barrio lines are salmon rated but someone on here who understands these things will no doubt chip in.