> If you use NRC bioavailability rates and to me it means natural is a little more than one-third more available, so to me the theory is that you should be able to use one third less than synthetic.

You have to be careful with statements like this. Normally, the vitamin E content in a capsule is given in IU and there is no difference between e.g. 400 IU of synthetic form of vitamin E and 400 IU of the natural form. Both have the same biological activity. However, the capsule containing the synthetic form of vitamin E will be larger since it contains a larger amount of fluid.