What are the merits of filing a patent before the end of the grace period?

BY grace period refer here is provisional application which generally files before complete application, the idea of provisional application is to allowed protection to true inventor on first to file basis, also in many cases we have seen the product prototype is ready but it required more testing and additional resources, sometimes fund, discussion, so during all these process inventors doesn't loose it right of true inventor, it also help inventor to seek additional time to develop the proposed patentable product I n all respects and file complete applications.

So you can say early filing gives you legal protection on your invention but nothing else, it's not assets till then it's been granted a patent and registered with IPO office.