At first, I didn't really like that. For one, it seemed way too bloated, to the point where it didn't mesh well with the match-ups within the story. Second, it seemed way too close to the most obvious and logical boost for Super Saiyan 4, which would be 500x base (SSj's 50x combined with Oozaru's 10x). I know GT isn't really important, but I care in particular because of GTR, and my "in-universe specialist" side likes to keep things lined up in that department, even within my own pet projects.
But now that I think about it, I think I know the reasoning behind claiming it's such a massive boost. And that main reason would be the inherent flaw in SSj3 -- the downright obscene rate at which energy is wasted. I think what they might be trying to convey is that even if SSj3 generates Ki a whopping four times more than SSj2... a massive amount of that actually gets wasted, and hence Goku isn't actually fighting on that level. With all the Ki that's essentially going down the drain, Goku's actual combat level might be considerably less than that; perhaps only somewhere between 200x-300x his normal form.
Let's pick some arbitrary numbers to test this out, and see how it makes the final battle with Kid Boo work out...
Son Goku - 25,000,000
- Super Saiyan 3 (full output, x400) - 10,000,000,000
Super Saiyan 3 (combat level, x250) - 6,250,000,000
Vegeta - 22,000,000
- Super Saiyan 2 - 2,300,000,000
So depending on how one might apply this idea, it could possibly fix a lot of the "problems" with the Boo arc's power comparisons. It even works with 500x for SSj4! The actual raw Ki generated by SSj3 might approach that of SSj4, but the form is so unusable, especially for the child-sized Goku, that it's useless. The gap ends up seeming huge when he reaches SSj4, which has all that power and more, but with no limitations in using it. Whereas SSj3 Goku couldn't lay a hand on Baby, Baby's punches are now ticking SSj4 Goku.
So, long story short: Super Saiyan 3 puts out an amazingly bloated amount of power, but Goku can't actually fight at that level because so much of that Ki goes to waste.
The one thing I'm still kinda stumped on is how the same concept may or may not apply to Gotenks; would more of his energy go to waste? Less of it? Or does that weakness ONLY translate into lessening his Fusion time, and not effect his power output at all? Or does he also have a significant energy drain, of which the reduced Fusion time is a direct result?
It could take some thought. One way or another, I think I'll try out this approach the next time I make a Boo-arc list.



) Vegetto, Super Saiyan