We don't have any 5WT lines here in Alaska (all in CA at the moment), so I put a 6Wt on the 5WT. You can't hold quite as much line in the air as with the right line (about 25'), but that's really no handicap. Loops are as smooth as butter frosting, and this thing shoots line like no 5WT I've ever seen, even if it's starting with the handicap of having some of the head still in the guides. I'll wait till we get back south in the fall and try a 5 on it before making a final call, but in the meantime it's going to get a heavy workout on searun Dolly Varden and pink (humpbacked) salmon.
As good as all that is, the story gets even better with the 10WT. I mounted an old 10WT Scientific Angler Tarpon line on it, and the rod just about jumps out of your hand, it responds so well to its rated line weight. More butter frosting on the loops, and it shoots line like a rocket. It's by far the easiest casting and lightest 10WT I've ever cast, and I've cast lots of them. The sensation is like casting a perfectly balanced 8WT. I held 30-35' in the air, slipped another 20' on my last backcast, then shot the rest of the line plus a little backing through the guides. In my geezerly state, it's been several years since I've been able to do that with a 10, and it's a grunt with an 8WT.
My wife has always had trouble with 10WTs, just not having the strength to load them well, with her casts going south any time she tries to stretch her distance. A 60' cast has always been her honest max, and she's missed too many ops up here and in warmer waters as a result. First time out of the barrel with the Boron IIIx she threw a 60' cast so hard that it ripped more line off the reel at the end of the cast. She pulled more line out and tried again. Second cast she knocked off an 80' cast with enough enthusiasm to turn the line over sharply at the end of her cast. Then she proceeded to do it again and again for another couple or three dozen casts without tiring. I'm betting that with a little more practice she can add to that casting distance. Don't often need such long casts, but when you need them you really need them. Even without reaching further, she's having a very easy time with her usual max 60' cast and no hesitation at all to stretch them to 80.
Like I said, when my principal fishing pardner is happy, I'm very happy. I can't find the right adjective for my own feelings when she's ecstatic!
One thing for sure----- If I want to fish with a 10WT Boron IIIX, I'm going to have to buy another. I've lost this one on the very first outing into our front yard.
209er