When you start talking about lubricants it gets almost as interesting as when you talk about motorcycle brands, everybody has their favorite. Ultimately we will all make our own decisions about what to run and of course there are different applications as well. I've not used ATF in the tranny, I'd considered it, but after reading Tucks post I probably won't. In my 4t I run Rotella T and change it often, in my 2t I run redline gear oil and have had great success with it, it runs cooler than regular motor oil, at least with an external temp. gun. As for 2t premix oil there are many that are good, whether they be petroleum, synthetic, or Castor based. In a previous post Tuck had talked about petroleum oil under a microscope, the key to petroleum oil is getting one that is TCWIII rated, this oil can be used in a outboard boat, they have babbit bearings and have to have ashless oil or it will trash them. I use a petroleum oil in almost all my 2t equipment, primarily because of the cost and the wear factor when motors have been torn down. In my snowmobiles they are typically run between 6-8000 rpm constantly and have never had a oil related failure, and I can assure you that they take more of beating than bikes do, dead weight, 500 lbs and wide open most of the time.
In the old days I think there was a huge difference between petroleum and synthetics, I don't think it's as apparent today.
As always, just my opinion