I apologize if my answer to the spinning guys question was flippant.
My first outings with friends on the Kinnickinnic were using spinning rod and reel. I did not fly fish back then. I would throw Panther Martins, Mepps, small Rapalas, and worms. We caught fish. We would cast and move, cast and move and covered a lot of water in those days without the understanding of the nuance of the sport. We were there to rip lips and eat our limit. The spring (back then opening day was the first Saturday in May)was the best for this method of fishing, or worming of course. As the season progressed into the late summer and the trout began to rise to the mayflies and other insects emerging from the stream. Spin fishing became inconsistent and much less productive as the heat of summer pushed in. Worms still worked but even they had lost some of their catching luster. The trout seemed happy enough and surely active with all this surface feeding. It was then, after being skunked on my favorite stretch of water, I was lucky enough to watch an amazing demonstration. A man in his 70’s who was fishing behind me caught trout one right after the other in the water that I had just fished through. As I watched from the cover of some tall grass, I could see him laughing to himself as he released each fish he had caught. He was throwing the dry fly. The right presentation for his time on the water to be successful at catching in that spot. He was kind enough to show me what he was doing. The next day I bought a fly rod. Hardware store. $15.00.
I went back the next day armed with my new rod and a box full of expectations to once again capture the crown of “The King of Catching”. I got skunked! The bugs were there. The trout were rising. I sucked at fly fishing. I just had not learned yet what I needed to learn in order to be successful at catching. I went back to spin fishing and carried the fly rod as my back up. It took time but I learned how to use the fly rod more effectively. Others were kind enough to help because it was obvious I sucked.
I realize I am not making a direct comparison from spinners to streamers and attempting to measure their effectiveness at catching trout. The direct answer would be NO, you should not expect the same results. Streamers thrown on a fly rod are not the same as spinners or rapalas thrown on a spinning rig. I have no good data to give you an answer. What stuck out more to me in your questions was the word expectation. If there is one thing that has helped me to be a better fly angler it is to not have expectations. Too many times, I went to the stream with expectations and was disappointed. Expectations caused me to be regimented, to be too narrow minded, to be too predictable. Having no expectations has allowed me to be much more observant, to be a better adaptor. Nature changes every day, every hour, every second. Notice the changes, adjust, hammer more trout.
I am going fishing. Last week I was hit by numerous Ice chunks and shelfs that were floating sneakily in the current. I caught no fish. Today nature is changing. She is warming up. I am hoping the trout will warm-up to my offerings.