RE: Cleaning ability of premium fuels vs. "regular"
Obviously, the answer to this question depends on the additives each company includes in their fuels, but I believe the increasing popularity of fuel injection (and finicky fuel injectors) over the last 25 years has narrowed, if not eliminated, the gap in the cleaning ability of premium-priced fuels over "regular".
Even if a given premium fuel had markedly better detergent qualities than regular fuel, the usual cost difference would be substantial enough to make this an expensive way to keep your combustion chambers clean. Instead of burning premium fuel for this purpose, stick with regular and buy a bottle of Techron (Chevron) every few months.
My daily driver has a Ford 4.6 V8. Manufacturer's recommendation is 87, I use 89, particularly in Summer, and pretend I can feel the difference.