The unite keynote today showed some features of unity 5 including the physically based shading and dynamic GI. Starting at 51 minutes. [ame="http://www.youtube.com/watch?v=5RZBxGexCuk"]Unite 2014 - Keynote - YouTube[/ame] And also 4.6 open beta is available with the new UI system.
You are writing off the cost of the software on your taxes, hopefully. I always add my Unity store income to my taxes, so I have a lot of writeoffs. The royalties for Unreal can't be written off. I don't think 5% is unreasonable, but that is a permanent drain on income and needs to be considered.