Thank you Gurjot for your reply!
Meanwhile I've sent an e-mail to the official ModelOff address and I've got this reply:
[h=2]Re: ModelOff 2015 - % of people getting through the first round[/h]"Thanks for your email. To be honest there's no real set cut-off one way or another. It can be generally be anywhere from Top 40% to Top 60%, depending on how strong people's performances are. We're not in the business of being overly harsh with this - it's more just a need to progress people who are competent enough to handle tougher Round 2 questions."
So, it's pretty much the same as you've mentioned above.
But thank you for the overall score that you provided that should be enough to go through.
Good luck if you are attending!