well it wont necessarily have to be a flat ratio, but maybe a goku at 1,750,000 would have at least a little more ki than goku at 750,000
in response to nretep, you obviously havent played against a piccolo or frieza who really knows how to abuse finger or eyelaser, sure it may take a lot of ki, but it also does a ton of damage, all you gotta do is melee them once and then eyelaser till your out of ki and they'll either be dead or nearly.
and talking about the speed based on ki, in the show, when someone who is more powerful usually is faster as well, and sure you might die a couple times at first (just like you sometimes do now when someone is a lot stronger) but then you gain PL every time you die so eventually, whether your getting wiped across the floor or not, you'll be pretty even (oh and btw, i realize if you get to some rediculous PL then ya it would be way too fast, and mess up the game pretty bad, so im thinking they would have a cap for the max speed of each transformation