Thanks for the tip! I will update the math on my site.

But I think you are also wrong. So, please, correct me again, or confirm this example ;-)

Case A: you invest 100 BTC using a normal sponsor
Case B: you invest 100 BTC using my Extra Bonus promotion

Let's suppose, for simplicity, that every account gets 10% of deposit during an undefined period.

In case A you get 100 * 10% - 30% => 7
In case B you get (100 * 10% + 100 * 10% * 15%) - 30% => 8.05

Case A break even time: 100 / 7 = 14.2857 periods
Case B break even time: 100 / 8.05 = 12.4224 periods

Case B saves 13.04% break even time.

Thanks again!