I use Mobil Delvac light diesel truck engine oil. I started to use it when I found out that it has the highest level of zinc allowed in modern engine oils. Zinc, as discused in the article above, repairs micro scratches in your steel components, which should ultimately extend the service life of the equipment. Most modern gas engine oils have very low zinc content because it is hard on catalytic converters and increases bad emissions over time as the catalytic converter is degraded.
The other two points in the article, common sump and slipping clutches, are non issues in my book. The fact that our engines have a common sump for the transmission, clutch and engine (as opposed to a car that has a dry clutch, engine oil and transmission oil) is not a factor because we change our engine oil so often. A transmission will likely break engine oil down faster than the internals of the engine, but replacing the oil before it is worthless will keep your engine and transmission lubricated well enough. I have not experienced any clutch slippage on my bikes since I started using the Mobil Delvac synthetic diesel engine formula that was not attributable to worn clutch plates or significantly higher engine output!
Regarding oil leakage, I have not experienced leaks in my engines if they have new gaskets. Old gastkets maybe, but only at the joints where old rubber gaskets have given up the ghost and where they were going to leak anyway.
Regarding transmission operation, I use 20W50 and don't seem to have any clunking or crappy shifting issues when the engine gets warm. That is also why I use dual weight engine oil... to keep the transmission working well after the engine has warmed everything up.
I change engine oil every 3k or so.
Disclaimer, other oils might have higher zinc content than the Mobil Delvac, but I am used to using it and have had no problems with it... and Hondaman recommended it!
Camelman