Hi Matt,
unless of course you are an idiot who has no fish fighting skills and you are playing a fish for longer than is necessary.
In an attempt to play peacemaker and prevent a cyber fistfight (I just hope I don't get punched for standing in the middle:)), I'm assuming the interpretation of "you" in the quoted sentence is any angler who fits the description as opposed to referring to Sayfu personally. Being new to the forum, I don't want Sayfu to take you the wrong way and feel insulted. I can tell from his writings he's a pretty experienced guy with a lot to offer.
As to the point of contention, it's interesting to see the difference in perspectives. I think you are both right. Huh? No, I'm not taking a stand in the wishy-washy middle, I'm recognizing the circumstances and context of the two positions. One is that of a working guide who is spending a lot of time on heavy water, perhaps most of the time fishing from a moving boat with fisherman of varying degrees of prowess (being polite). The other is of an experienced/competent angler who knows how to use his tackle effectively. For example, fishing the Lower Sac the way it's commonly fished, I can't think of a guide that wouldn't discourage the use of 6X, if for no other reason than it isn't necessary to fool the fish. Guides always prefer the heaviest tippet possible, though even that's no guarantee. I've had rods in the boat that would kill 18" fish using 3X! Deft boat handling and skillful use of a long handled net is the only way some fish are brought to hand. The concepts of rod angles, proper pressure, line control, and keeping their heads up at the surface escape them. I think that is the context in which Sayfu meant his comments since he did reference "the water he fishes".
I won't comment on the waters you fish back East, But I agree with you that 6x is both practical and sometimes necessary for fishing hatches of ephemerellids and baetids on rivers like the Missouri. For those that don't know, the Missouri does have it's share of heavy water and big fish, though it's amount of heavy currents are not comparable to the Madison, Dechutes, Lower Sac, or in Sayfu's case, the South Fork.
Regards,
Kurt