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Kevin,
What you're suggesting (leaving the FF extra rich during the cruise climb) is something Walter advocates - and told me I too would be convinced as to why this is a good idea by attending the class. Let me tell you, he delivered on that promise.
I now leave the mixtures full rich during cruise climb to make the cylinders run much cooler and to increase the detonation margin. This equates to about 19 to 20 gph for cruise climb vs. the book recommendation of 15 gph. Let’s say you climb to 7,500 feet at 500 fpm – that’s only 2.5 gallons extra. Even climbing to 15K’ will only cost an extra 5 gallons of “excess” burn. That’s pretty small considering our tank sizes. Previously, I used to have to carefully monitor CHT's in the climb and tweak airspeed and mixture to keep them under control. That is simply a thing of the past.
Regarding your other point about running at peak when at 65% power, GAMIs don't make this worse - but in fact make it better. By definition, peak is the point at which the maximum EGT is achieved. And richer or leaner will result in a cooler EGT. With the Cessna gage, when one cylinder reaches peak, you have no evidence where the other 5 are - they might be leaner, or they might be richer. GAMIs are tuned so that all cylinders peak at virtually the same fuel flow. That means when one of the peaks, they are all very close to the same point - much closer than if you weren't using GAMIs. That said, at 65% power, I don’t think the red box exists.
The uneven fuel distribution (while true) is a red herring. The reason for this is the design of the engine resulted in uneven air flows to the cylinders. In order to reach the optimal fuel air mixture, the GAMIs match the fuel flow to the engine’s uneven airflows. If all cylinders are at the optimal mixture, then they will all peak at the same fuel flow.
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