Been Evaluated and Abandoned For Good Reason
You have 0 basis on the gravity issue. It's NEVER been tested. We have 1g+ data and 0 g data. People weren't on the moon long enough to seperate out .16 g from 0g.
On Mars you have a planet blocking 1/2 of cosmic radiation. Oneil colonies will have to be very massive to do that and will be far more difficult to build than a Martian colony with resources available by a walk or drive rather than a rocket. You have no enginnering sense whatsoever to think an Oneil colony is easier. It's an idea that won't come back in broad favor until space technology makes it far easier than it is today. The idea was abandoned for the near future because engineers realized how truly difficult, expensive, and impractical they would be.