Thanks for the info guys.
I'm not hung up on ester based oils, It just happened to be an ester based semi-synthetic oil that was recommended to me by someone who's been riding and fixing these bikes for a long time. He's a local dealer, very involved with the local club, donated much time and money to our sport over the years and generally nice guy. I don't think he would claim to be an expert on oil, nor did he claim that it was the best available, but he did say it had been working well for guys, and it was reasonably priced.
I didn't know was ester based oil was, or what the characteristics were, which is why I started the thread. So now I know a little more, thanks again for the info.
My bike is liquid cooled. I see a lot of references to ester performing well in air cooled bikes, so maybe that that is one characteristic that isn't relevant in this application. Also I am riding offroad, mostly tighter technical woods type riding, so I am generally pretty low RPM's. That being said, I still like to change my oil pretty frequently. I figure that oil is cheaper than metal. I try to change the oil after 10 hrs. of riding.
Any recommendations I am all ears. I'm always eager to find out what works best, and if there is a difference, one brand/type over another, I think it's worth paying extra for. (within reason) Quality oil is cheap insurance.