Chaz
I 100% agree with your previous post, I have noticed this same type of pattern. I think in many brookie streams the forage can vary greatly, and there by limit your sucess on a fly atempting to imitate a non-existant food source. I have noticed on streams with good minnow populations ,chubs, red finn's etc. that you can really vary your streamer approch. white buggers, BND, you can even get away with crazy stuff etc. I have also found that these flies seem much less effective on the colder freestoners where the only food base is bugs and other trout. Like you said, a little trout imitation usually will work much better than a minnow imitation.
One thing I due almost religiously now, is when I get to a creek, I will spend my first 5 minutes flipping rocks, basically looking to get a grasp of possible flies. it will tell you color and size of nymphs, also if crayfish, or minnows are present. I have found taking the little bit of extra time to do this really helps my confidence level when I put on a fly that is the mirror image of some sort of forage I just found present in the creek.
~5footfenwick