Looking back at my notes, I do think that the experiment cost me some fish. The practical size limitation of the flies was the most common issue, it's just not feasible to tie a silver outcast 20cm long for bass that are keyed in on large ayu. Even with long enough hair, they'll foul half the time at least. Sometimes the bass would eat a smaller fly while chasing larger bait, but they would often move towards the fly before rejecting it - it could have been retrieve cadence, speed or some other factor, but my feeling is that it was size. As the season progressed I also noticed that profile seemed to become more important too, fish feeding on Japanese chubs and crucians became far less willing to eat a fly that was the right colour but wrong shape. Probably because of fishing pressure and the Japanese bass angler's obsession with finesse fishing to deal with pressured fish (another reason I like big flies).
The other way, the experiment cost fish was hooking. I was pretty much expecting this to be the case but wasn't sure at what size fly it would become an issue - it seems to be about 7cm . I've noted 7 separate occasions where I watched fish hit the head of the fly and not get hooked. It probably happened more than I saw too. Anything under this size then the long shank required to prevent fouling seems not to adversely impact hookups. I'm looking forward to getting back to my BTDs with the hook in the front end.
Weight is also a bit of a problem, split shot is something of a work around, but I'm not keen on it, nor do I necessarily always want to fish a tip to get down as a floater with a straight leader and compact, tungsten rich fly is often a better option.
Much of this was fairly predictable, but it was good fun to play around with the flies and confirm my suspicions. This season's box is going to look very different but there will still be an assortment of little bucktails in there as I think, with the modification of dropping the wing around the body, they're probably the best small bait imitations for running water.