That said, I'm still uninterested in using Unity because of the implications of having a black box engine that underlies your project. Being able to step into the engine code is too important to my understanding and my ability to debug problems, not to mention the possibility to implement your own bugfixes or otherwise modify the engine.
In addition, the collaboration story with Unity still isn't great once your team scales past "tiny." Unreal and its Perforce integration were built and battle-hardened in the forge of AAA studios with hundreds of artists; Unity still encourages you to use a proprietary "Asset Server" which they charge extra for, and even then it gets awkward and prone to irreconcilable merge conflicts once you go past two or three people on a team.
Having said all that, yay competition!