Yup, I'm with Fordie on this one.
My bike has a scottoiler fitted, used it consciensciously, and the last chain did about 12,500 miles...so not much extension in chain life and not much pay back for a system that's a real fiddle to get regulated properly and doesn't cover the side plates with oil even when everything else is correctly set up. It seems to me that what the scottoiler does best is splatter much of the left hand side of the bike with throw-off from the chain, it covers the crankcases, swingarm, hugger, rear wheel and left hand seat panel quite nicely, but still won't cover the side plates on the chain...
My chain lasted ages, with no adjustment and I really thought the scottoiler was going to do it's job and give me the double chain life that some report, but then it degraded very quickly at about 11,750 and I was adjusting it before every ride.
The only downside with the WD40 option is that you have to do it regularly, I didn't have time between last weeks rides to work and Sunday's rideout, and sideplates get surface rust on them in less than a day!
Still, it's no more regular a task, and much less of a task, than wiping all the muck from a scottoiler off your bike so no excuses really