One thing to keep in mind when trying OPRs (Other Peoples Russells) or Mayer seats for that matter, they will probably not be as good as the one you have built for yourself. What makes a custom seat so great is it is built for your shape and riding posture. Plus, if it doesn't measure up you just send it back for a free adjustment describing what the problem is. I had to do this on my FJR seat. Upon first build it was canted too much forward and slid me towards the tank. At 6'2" that was definitely not what I wanted. I had them scoop a little foam out from behind and create a deeper butt pocket and it has been 65k miles of bliss from then on.
Some folks have had problems with their Russells but when queried you'll find that they were unwilling to go through any adjustment process. They just tried to live with the first delivered product.
No "off the shelf" seat will measure up to a custom. How could it? It isn't shaped like your backside, but rather the average backside, on the average shaped rider, in the average riding position. People say that they think those others are good enough for them, but they just aren't being picky enough, and have also probably never spent the money for a custom saddle. Once you do it, you'll never think about Corbins or Sargents again. It's only about $100 more for a custom seat than those off the shelf aftermarket ones.
Some of the sporty crowd will dis these custom "tractor" seats because it makes it
harder to slide your ass inside on corners. That is definitely true. Notice I said "harder", not impossible. It can definitely still be done with just a little more effort. Plus more than half of the riders you see making the ricky racer seat slide antics are simultaneously shifting their torso back toward center anyway, and putting their head up with eyes level to the horizon. If you just leave your ass in the middle and shift your torso to the inside of the corner, put your head in behind that inside mirror, you'll get more important mass transfer to the inside than by hanging your ass off.
Of course YMMV.