I think palmer discusses that the yeast only grow to the "size" of wort that they are in.
I also think some of the really big mr. Malty calculations are outrageous. Unless that beer is going to be 10% or something, I would think a gallon starter would do.
That is not a scientific comment, but just one based on read others comments.
I have done 1 gallon starters on big dubbels with good success.