Yeah, the "climates" thing sort of cracks me up, too. What temp is that intake manifold, exactly? ;-]
I used to work on a tank-farm, as a mechanic/hand (great job to pay for college, interesting, and mostly hazard-pay), and we transferred LOTS of fuel between various companies, the "trading" was CONSTANT, whenever someone got low, for distro.
This applied to fuel being sold to the airport, military, and gas-stations, it ALL got mixed.
Supposedly, some places re-mixed their additives, after receiving it, but if that was the case, then we often got their "post mixed" fuel sold back, to us (not naming any specific fuel companies here, but I can say it covers most of the "big players"), also pretty regularly. Perhaps they re-mixed the mix, when we sold it back, but at some point it gets a bit "weird", if you ask me.
I know I've seen various "test metrics", the standard ones used post-transfer, and they rarely varied, at ALL, even after we got a "big push", say from another company that was "known for their additives"...
The only fuel that was treated really carefully, IME, was the AV-Gas, intended for (partly turbo) prop-planes, which was often in the 100+ octane range (also used in really high-compression race cars and such).
I'm sure if you use an aftermarket tuning package, that advances the timing "enough", with an XT-turbo engine, you would see some benefits (to using >87). The downside is that if it can't de-tune enough, too, you'll get a fair amount of "knock", when using 87-ish fuel. If/when these packages exist, I'm sure those aftermarket tuners will publish the numbers, showing the improved torque/HP curves...