That they look better in one OS compared to the other is actually irrelevant. Ideally you would have a good measured profile for each. If you're setting it up to match prints, you would turn the display down until they match under consistent lighting. You can go much further than that in terms of color management, but that would at least be a start. Just don't assume that suggestion to be an exact science.
What you mention is dated by many years, and it's the worst possible advice you could give anyone. I am just typing this because I don't want to see people run into more problems due to misguided words. Even Apple ditched the gamma 1.8 default with Snow Leopard, and none of the hardware they've used in recent years would work well at that setting anyway. You can dial whatever you want to in profile instructions, but that doesn't change what is available from the underlying hardware, which is designed to be run at gamma 2.2.