Doug,

I've had good success with these.

I do find that putting that 'bright spot' of color in the thorax area catches more fish for me than ones without it.

I don't go overboard, just add a bit of chartruese dubbing in that area to an olive nymph, a bit of bright orange to a brown on, and a bit of bright yellow to a cream one, etc.

These are great 'all purpose' flies for me, they work in moving and still waters.

Good luck!

Buddy