I did try varying the colour and sizes of the EHC. I have colours: black, tan, orange, yellow. Fly size definitely could have been a factor; I think mine were too large. Honestly, I never actually saw fish eating caddis, but with them landing and scurrying around on the water surface I just went with the EHC. I think I need some courses in entomology!
Yeah I find fly fishing to be far more enjoyable than chucking gear, even when I'm not catching fish.