I'll always start with something that looks roughly like the forage species, but I'm willing to change to something more shocking if conditions dictate. If fishing more than one fly I'll almost always fish something imitative in conjunction with an attractor. I really belive in the power of the attractor to make fish eat the more natural offering. But I read Lars' post just after tying a batch of mulkkis/glimmer shrimp and pattergrisen it got me thinking about what a lot of us think imitation is. I regularly see these flies being described as shrimp imitations, which is nonsense. The mulkkis especially is just a blob kidding on it's a shrimp imitation.
I sometimes wonder about this kind of thing when I see a lot of flies, or even conventional lures. There seems to be an culture among some where catching a fish on an imitation is somehow better than catching one on an attractor, which is probably why many of us engage in the fiction that our neon magenta mulkkis imitates a shrimp. I don't care either way really but I wonder if it's something that could cause you to struggle when actual imitation is important. Who knows?