I have 5 STH reels and am very impressed with all the models except for the pop cassette model. It is a little too loose for my tastes, although a very serviceable reel. As to the reel with the turbine drag, it works exactly as advertised, and I have never had a moments problem with it. I can set the drag at the lightest setting and the drag will increase as the fish pulls harder. You only have to use the manual drag if you want to horse a fish out of the weeds. My reel which has the turbine drag is the saltwater model, all metal. Haven't tried the ones with the plastic turbine casing. STH/Cortland service is top flight.
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I only do what the voices in my flyboxes tell me to do.