All those graphical features are present, and many others, by default in UDK. In Unity, things like night and day cycle, dynamic GI and others are available at low prices at the Asset Store. Leadwerks has most of them as well, check the new version.
Also, judging by your EULA, it's only free if your game is small. It's similar to UDK's licensing, but i'm guessing that if i have to chose a middleware for my $100,000+ game, it surely won't be an unknown engine by an unknown company with no released games in the AAA market. It will be UDK, or even, a custom Unreal Engine 3 (or even 4) license. Do you see what i'm trying to tell you?
Your current business model is broken. It's free, but not really free because you have a flexible pricing based on each customer. So, you're not competing directly with Unity or Leadwerks, because they're much better and cheaper alternatives for indie. Apparently, you're focusing on big budgets, but in this case, the engine benefits are not comparable to UDK's, which has a much better product at the same price flexibility. And if you have a big budget, you want heavy support and a heavy name behind the buck. There also CryEngine.
So, if you're aiming for the big guys, you clearly can't compete with UDK or CryEngine in terms of product quality. But then, you try to compete with Unity and Leadwerks, and although comparable in terms of features, their pricing options are much better for indies. You stand nowhere in the middleware market. That's what i find curious about S2 Engine. And that's why i believe that open-sourcing this could be a much better option for your product. See Torque 3D and their market boost when they released everything under MIT.
ps.: No networking?