I very nearly Replied, in attempt to answer... then I thought, Uncle Phil can say it better than I could.
Well, I will explain it since it has become a 'topic' of sorts - but that doesn't mean anyone will understand it.
The reason is quite simple and it does not have to suit anybody but me (BTW I do know how to remove a ST1100 seat ...
) -
I have all four bikes set up and equipped exactly the same down to the tools in the tool bag in the right pannier.
I don't have to move anything from bike to bike except me!
So when I go for ride - long or short - it's pick one and go based on length of trip and how much tire tread is needed.
Now all 4 will have their own Russell seat so I don't even have to swap the seats around.
That's the way I like it and that's what matters to me.
And it also spreads the wear on the seats out amongst them - sort of like swapping tennis shoes instead of wearing the same pair all the time.
I was talking to Jay at Russell and he says they usually see seats back after 80,000-100,000 miles from most folks.
On a different topic, I also got to talk to Terry, the owner, and found out the entire history of the company and such.
Really interesting stuff as how RDL all came about.
My first RDL was probably one of the first that was built when Terry bought the company as I had sent it in to the 'old' Russell.
Terry had bought the company in the mean time so his staff ended up being the ones that built it.
They do a really great job and my new one is the best one so far (and is the fourth one they have built for me).
I highly recommend doing a ride in if you can.