Yeah, I don't know. I've had/have two R1100S with well over 150k combined on them. I've run about every spark plug that will fit in the hole. Only time they get replaced is when the electrode is gone. And trust me, I've run them to the size of pencil lead. What makes a huge difference on those bikes is taking the time to really tune and synch the throttle bodies. I have never had a surging issue on a stock R1100S which was notorious for surging. I've also tuned it out of RTs and 1150GS by the same methods. None of the 1100/1150's should surge stock. Surging in modern computer controlled bikes is caused by the bike going from rich to lean as the computer tries to maintain a certain fuel map while looking at a lot of variables.
As for longevity in spark plugs with the FI bikes, the BMW plugs seem to last the longest. I think I just have NGK's in the airhead, but have used champion and autolite, and really, they all last a really long time, carbon and oil fouling aside. We are talking about bikes that are 30 or so years old. They just weren't weren't made to run on today's gas all the time. If you want to see a real improvement right away, go invest in some pure gas, and by some champions.
It's eight and a half gallons of gas; and an engine. What more do you need?-- BMW R80G/S
Save lives. Legalize lane sharing.
Cow eyes don't glow.