I live about 600 miles south of the border. I have no reason to head up there, as I have a lot to see down here!
Eventually I will, without doubt. When I do I will pick my routes and areas carefully, and probably find someone to ride with who knows the region better than I do.
As we keep saying, it's also about mitigating risk. The northern border states are riskier to ride in than down here, so until I have seen all there to see in the South, I probably won't go there.
If you want to get to the safest parts of Mexico, you have to find a way south. If you feel it's too risky, you shouldn't do it. That is your risk management process.
I was going to buy a bike in the US last year and ride down. If you check my first ever post you'll see I went looking for advice and a group to ride with. In the end I went to Canada on a contract, and then discovered I couldn't return to the USA (visa issues) so I had to buy here
Anyway, don't pay any attention to me when it comes to the north. Follow the advice of the guys that live there (and certainly not people living in Europe)