The long idle test lets you know exactly what is going on in the engine, so you can just bump it up a bit richer if that's how your engine runs. It also gives you a good decision point where you can live with a slight stumble during transition, or try a hotter plug. The for real test is flying the model around and listening to the engine. How does if fly? How is it at half a tank of fuel? The burbly, or wet sounding midrange is too much unburnt fuel. I try to stay away from that condition if I can because you can get into trouble on those long approaches where you may be near idle for 20 seconds, or longer. Having a loaded up engine when you need a go around right this second is asking for trouble. Just my way of going about it. Nothing better than a good carb that tunes well. But it's clear that you know what you are doing so it's just an opinion.
