If everyone went straight to Aubagne than yes it would make it more crowded because all the other recruit centers would be empty and everyone would be in Aubagne....but, I'm going to guess that not everyone will do that.
If you go to Paris first, you will still end up in Aubagne and going through medical, sportif, and the interviews again no matter what. Remember, some people are going to be showing up unprepared, some will be going in blind in what to expect. Many will not get selected because of this. The benefit we have is this forum and other online tools that we seek out to be better prepared. Not all volantaire's will have done their homework. I wouldnt worry about Aubagne being over crowded with competition, just more so in being more prepared than the competition to get selected.