How has making the source code available for all has made Unreal 4 a better engine?

Hey Epic,

I have a few questions about Unreal Engine and how Epic has benefited from the open source community. That said I am not sure about what to label this as so I am putting this under community. I hope that this is OK.

  1. How much money has Epic games saved (Ballpark figure of course) by making the source code available to everyone?
  2. Unreal Engine has thousands of new pull requests a month. How many of these pull requests are new features opposed to just general fixes?
  3. Would you encourage other companies to open source their game engines? If so why?
  4. What are some of the Pros/Cons that the team at Epic Games has run into since making the source code of Unreal 4 available for all?
  5. Would some one at Epic be willing to to do a detailed write up on this?

Just curious,

that’s a marketing, but for a big but not giant developers open source is huge

It has really helped the people on Linux! That’s for sure.

It also is just great to have it there. I mean, someone from the community might figure out a problem and fix it for Epic. Saving everyone time and money.
I would say that it has really put UE4 above the other Engines. But that’s just my 2cents!