I agree with Daveg . Also when i,m not having much luck I add a small splitshot or a weighted fly toget in the zone this usually improves my luck.

 P.S     I fished the past 5 seasons with a 7 weight  with little problems

Isn't that if you were to fish the same depth as the fish's mouth?  If you were to fish the water column just above the fish then you wouldn't have that scenario.  The higher your presentation is from the fish the more likely more fish will see it. (The cone theory for a fish's vision).

I've always heard on the hotlines to use a long leader,  split shot and rolled muddlers on a dry line.

Just because a sink tip is used... it does not mean that it is fishing the exact depth of the fish and all people using the sink tips are flossing the fish?  If that was the case, I'll bet that you couldn't buy any sink tip line because they would be all sold off the shelves.  (Could you imagine a line that would automatically go to the fish's mouth level?)  Could it be possible that they are also fishing the column just above the fish?  What would be the difference between using a float line, with long leader, with split shot vs. using a sink tip line???

I catch sturgeon on green wool.

Firstly we are not talking about fish specifically we are talking about Coho.

Secondly it depends on the kind of water you are fishing not if you are fishing a sink tip.

Thirdly you can do the math and figure out the sinking rate of a type 6 vs a small shot on your line, I don't have time.

Lastly I don't fish fast water for coho and I also don't use shot on my line.  How long have you been hooking Coho on a swung fly and do you get them on dries too?

Firstly I know we are talking about coho specifically at the mouth of the vedder.

Secondly I agree it all depends on the type of water condition.

Thirdly my point is that in your post you make it seem like all people who use a sink tip are flossing the fish.  My point is that just because a sink tip is used it does not mean that we are flossing the fish.

To answer your question about how long I've been chucking flies for Coho...it's been about 12 years since I chucked my first fly for a coho.  I've never gotten them on a dry fly, but I have on my dry line before.

Tee Hee...moot point.
If your name was Ed, it woul be retard-ED