Home One's Canon size was originally twice the length of an ISD, and has been slowly shrinking over the last decade. Even the Rebels concept art shows it as longer than an ISD. Tis isn't the case with the MC75. I am also of the opinion that the MC80 Liberty just barely makes the large category and it is nearly the same size and shape as a Venator. I would also put the MC80A (wingless Liberty) in the medium category just from reduced volume compared to the Liberty. Length can't be the only factor for determining base size. Volume and durability should also play a role.
Just my two credits.
