1) The claims by motorcycle specific lubricant manufacturers (and the dealers who sell their products) that automobile/truck specific lubricants will harm your bike are outdated and blatant "fear mongering". Oils like Shell Rotella T, Castrol, Mobil 1 (and others) have an excellent and proven track record in bikes.
While the refiners you name do make oils that are suitable for use in high-performance motorcycle engines, they same refiners also make other products for the automobile market which they themselves recommend against using in motorcycles in some cases. For example, Shell states that their Rotella T Syn 0w-40 is not shear stable enough for use in a an engine sharing oil with a transmission. Friction modifiers remain an issue as well, and Energy Conserving oils should not be used with wet clutches.
It was the manufacturers of four stroke motorcycle engines, principally Yamaha
, that asked for the creation of the JASO MA and MB oil standards in order to preserve the availability of oils equivalent to the API SG/SH grades. Their concerns over the reduction of phosphorus and zinc anti-wear additives are as valid now as they were then, and I don't think you could truly say that they were guilty of falling for unfounded fear-mongering.
On the other hand, it is also true that there are a good many oils which simply have never been tested for compliance with JASO that are even outstandingly good in motorcycle engine/trans applications. Shell Rotella T Syn 5w-40 is one. The only trouble is that without the presence of JASO MA on the label, you are left to rely on your own research, or on the experiences of other users.
3) The difference between 1000ppm of an additive and 1380ppm of the same additive is insignificant and a marketing ploy. (ppm is parts per MILLION)
Then again, that's a 40% increase, or a 30% reduction, depending on which way you go with it. Whether that's significant depends on the additive. There are levels of some above which there is no increased benefit (or, carried to extremes, even harmful), but also below which they become ineffective.
4) The majority of bike riders/racers change their lubricant before it needs to be but this is a case where it is better to err on the side of caution.
This usually the case, at least in terms of the level of contamination by foreign material. But in terms of viscosity loss due to inadequate shear resistance, some oils can be degraded suprisingly quickly. I know of at least one oil sample of a 10w-40 that went to 7w-19 in only 5 hours. Most of the good full synthetics won't do this, but those with a very wide ratio of high to low viscosity are suspect. 4:1, such as 10w-40, or 15w-50, seems to be about as good as can be done with synthetic base stocks and no viscosity index improvers. To go beyond that, VII's are required, and they are somewhat fragile. This is the one test result I have not seen on a sample of Rotella T 5w-40. (I'd really like to, too, if anyone has one) But 0w-* oils should be avoided on that count.
6) I have never met anyone who had a clutch that was in good condition, used an automotive oil and experienced slippage problems due to the additives in the oil.
I have. It was an EC synthetic, and the problem went away after he changed oil. More often, I have seen oils that made the clutch "grouchy". That is, the oil caused grabbiness and/or dragging behaviors that cleared up when the user switched oils. None of this happened with an MA oil.
Not firing back...just commenting. Mostly I agree with you, particularly in the assertion that how well you maintain the oil is more important than which oil to use.