I am very interested in this as I only drink alternatives now and although not very much I will often eat foods made from the same ingredients (soy, almond, etc).

Glycemic Index - Are we talking about sweetened milk alternatives here? From what I have seen most alternatives come out the same or lower than dairy milk unless they have added sugar.

Vegetable Oil - I am sure alternatives contain more vegetable oils, but interested to know what you mean by "really really high". The opposing side is dairy milk containing saturated fat which has it's own implications.

Would love to see some studies if you have any handy.