This is a brilliant decision. I attended Startup School this weekend, and used the event and the surrounding parties to pitch our idea to at least 10+ Y-Combinator startups. Every time i pitched our company i learned something new and got great feedback on how to pitch it better next time. Startups that are concerned about this, should realise that to be accepted to Y-Combinator is not the goal of your startup. It is more than everything else a great test for yourself. Are you able to explain your idea in a couple of sentences, do you have a great founding team, is there really a market for what you are building? Trust me, when i remind you that making your company succeed is much harder than filling out the Y-Combinator application form.

Having other startups validating your idea is a great way to actually proof your team, competence and idea. We're based in London and despite the fact that we were lucky enough to know a couple of YC startups, that gave us great feedback on our application, we're thrilled to know that our idea, our team and our startup will be reviewed by a couple of other great YC startups.

Mark Zuckerberg, probably put it best during his Startup School talk. He told the audience that instead of going for the universities that really wanted to use Facebook, they rolled out Facebook to the universities that seemed the least interested in it. I think this is a brilliant move to test your product. The same applies here.

Good luck to everyone!