Most of the problems with the 575 were reported to be on the bottom end.
The 576 is a reworked version which lost a bit of weight and gained some more power.
Having owned both the 372 and the 576, I think the choice really depends on your applicaiton. The 372 is lighter and easier to maneuver. If you need to fell, buck and limb out trees then I'd rather do the limbing with a 372 than a 576. For a saw to work a woodpile, or to buck larger stock, or for felling, but less limbing and light detail work, a 576 is where it's at.
The autotune units reportedly deliver better performance over a standard carb unit. They have been reported to take to mild muffler mods. I dont think anybody has tested to see where exactly the flexibility of the autotune chip maxes out.
Cutting with a 441 M-tronic today, I did notice that there is a much broader powerband, as the saw is optimizing the fuel air ratio to exactly what youre doing, as it's happening.