Lots of good points being made. It just occurred to me that nobody has addressed what I think might be the best reason to fish a weight or two above the bare minimum: While you may be expecting fish between 6 and 10 pounds, and that may be a very reasonable expectation, Nature does grow 'em bigger on occasion, and sometimes, the occasional freak is the fish that comes to play. When that happens, in all but the very softest of water, you won't be able to turn that fish with a 6-wt. Then, you have three choices, none of which is ideal: 1. Break the fish off. It seems some of the posters here have caught so many steelhead that they don't mind doing this. I've caught my share, and I would still much rather be able to land that fish. That way, I get a close up look at a cool fish, and I get to keep the fly that fooled it. 2. Break your rod, which may be fixable but will likely never cast the same again. When you start hearing a creaking sound, this is about to happen, and it's not cool when it does. 3. Pull as hard as you can without breaking your rod and wait for the fish to exhaust itself. If it's a wild fish, it's as good as dead. If hatchery, its flesh will be considerably less tasty, due to acid buildup. Why leave yourself open to making this choice if it's not necessary? For the record, I'm not suggesting that those saying a 6-wt. is sufficient are wrong. Many of them may be more experienced than I am, or else they may have the healthy attitude that a hookup is cool enough without dealing the deal every time. Only speaking from limited, personal, subjective experience here.