I have no idea why some Colorado owners don't experience the same chuggle but I bet that the RPMs at upshift are the same for the non chuggling truck vs the chuggling trucks. The variation in ECM adjustment to gasoline type might be different for some of us to the point where 87 does not produce enough power to keep the engine smooth at low RPM but 93 does. I am the living experience with some others on this forum that reported no chuggle with high octane.
First, not going to dispute any of your thoughts, but my take on this specific question you raise has to do with driving styles. It would probably be hard to quantify, but I am going to assume that the majority of you who see the "chuggle" effect would probably be classified as an aggressive driver versus a more laid back driver.
In day to day driving, I rarely see a problem. Last night, I had to be at an appointment at our church for 6 PM. Left Fort Worth a few minutes after 5 PM, should be no problem, but I failed to take into account that the Fort Worth Main Street Festival is this weekend and they have already closed off half the streets in downtown. Traffic was horrendous as people tried to jockey around all of the street closures on top of all of the construction. So, I wasn't thinking about hyper-miling my way to my destination, but was driving much more aggressively. I noticed a lot more of an issue with chuggle.
Not saying that a driving style is right or wrong, but rather, these trucks, and a lot of the newer designs, are programmed to lean toward a hyper-mile style of driving to maximize the MPGs and the more aggressive driving styles do not match up with the program.
I don't see enough of an issue to pay the extra $$$ for higher octane. I did try a couple of tanks of "real" gas without any ethanol, didn't notice any change, but I was towing a trailer, so might not have been noticeable. I also tried some higher octane a couple of times when it was priced similar to Regular, couldn't tell a difference in one tank.