Some of us already had this discussion and it seams it does affect the stability of the tower. We even made a mod making all balls equal but decided not to publish it because in a way it was cheating. It wasn't fair to people that didn't have/won't use this mode.

Do somobody use this mod who are in the leaderboards or they will be deleted from there?

Hmm and can you say me if im right with the ball sizes becouse im making now a segregation of all 300 bals, and i think there is one more size but im no sure, you?

Edit.
I noticed too that the size of Goo Balls Change when i exit and enter the World of Goo Corporation ://
Someone have an idea what can i do?

There is nothing you can do. It's just the way it is. And anything you do will be like cheating because all payers must be equal in World of Goo Corporation

But can i segregate the balls, or it will be cheating to ?
Then i make the tower without exit.

What if the "same size ball" addin was in the next version of gootool, like the billboards goomod?

You can seperate the balls if you want... but it won't help (much)
1) Big Balls weigh exactly the same as small balls!
2) Big Balls do not have stronger or Longer arms than small balls

The only difference it makes is the balls you have touching the floor.
So if you found 10 balls all the same size and used them touching the floor...
and build the whole tower in one go.. without saving... it "might" help a very little bit.. but not much! And I wouldn't say that was cheating.

The main problem is when you do save the tower, then when you come back they have all have changed to random sizes.
About the only thing you CAN do for that ... is "live with it!"

We already have this mod mod here at goofans but it isn't published and it will never be. That wouldn't be fair to kamal and so many others that didn't have this mod or to someone how won't use it

oh, then don't publish!