Operate your aircraft in accordance with the Mogas STC. If there are limits, follow them. I would be suprised to hear that there are still altitude or temperature limitations associated with vapour lock, but I don't know all the wording of the STC's. In the very early days a few approvals did have altitude and temperature limits, but I believe these are long gone. We did a lot of testing to confirm that (for many Cessnas anyway) such limits were not required.
That said, I fly 100% Mogas all the time, unless I'm away, and have to refuel with Avgas. I have done flown Mogas in my plane for 23 years, and 2600 hours. Add to that, another 500 or so in other Mogas powered aircraft. In the 182, I'd fly out on pure Mogas 5 hours, and back on a fill up of Avgas. Some days were 70F at 11,500 feet. I never had a problem.
You will not notice any operating difference, other than the cost.
First: Follow STC limitations and instructions,
Second: Use clean, fresh Mogas, obtained, transported, and handled safely,
Third: Don't worry!