If you look at miles traveled verses accidents I suspect the superslabs would be safest places you can ride, statistically speaking. As Dave says, fewer opportunities for cages to pull out in front of you or turn left in front of you. We have a lot of "scrappers" in this area and I've had scrape sheet metal, plywood, you name it come out of their pickups and into my part of the road as I approach to pass them and worse, as I meet them going the opposite direction. Always on highways and county roads though. They mostly seem to stay off the interstates around here. I've had bales of hay or straw fall from trucks and into my lane as I was leaned over in a curve and once a log chain dragging behind a truck swung across my lane in a curve like a skier behind a boat. I had to go right to the edge of the pavement while leaned over to avoid that one. Also once had a motorhome's tire we were meeting on a mountain road (Yellowstone area) explode and slightly injure my riding buds foot with a big chunk of the rubber that showered both of us.
My opinion is, if you ride long enough motorcycling will always be fatal. So will driving, working, chasing the ol lady or any other activity because life is always fatal. You will die, and you can't escape it. So you do your best to put it off as long as possible while still having fun.
Having seen it happen both ways too many times, I think I'd rather go out when I'm still having fun than long after the fun has ended.