My Russell Day Long with backrest has been on for at least 15K. I found their "day long" claims to be true. I recently returned from a month of riding that totaled a bit over 12K miles and I'm very satisfied with my seat. I chose to go with the canvas insert and I'm pleased with the comfort of canvas and how well it breathes. I do need to cover it when it rains and that is the only downside. No seat height issues or other issues.
With the "pocket" to sit on I now sit more in the bike than on it. I'm better connected to the machine and would purchase the same again.
Happy riding to you