You mean vertical sync? When I look up to the sky the FPS goes from 30 to 40 in some cases and stays there, and from 60 to 72 in others. So there's no cap.
As for the comparison I'm suspecting they don't want to make some facts public -- imagine the impact. For the moment, one is easier, the other has an extra feature, bla bla blaaa... you know, it's arguable, one likes the features, other prefer workflow... can't say one it's better than the other so a comparison can't be made as there's no solid criterion. But when it comes about speed you can tell not only if one particular engine trades speed for workflow (like say, scripting replacing C++) but more important -- you can tell very much about the architecture, if it's well done, even if the engine uses scripting. Conversely, even if an engine is C++ oriented but has an improvement of only a few FPS then you can tell that it's not worth it. That's why we need a common denominator.
You had to learn their performance issues by practice, I suppose. and it's clear that you know what you're talking about.
About the large texture in C4, you made a point. Actually, it was (one of) my favorite. But I saw this video with a large, actually humongous spaceship on YouTube in Unity compared to C4 and the results were propostruous. I liked C4 for the voxel terrain. Again there's the default example with the graveyard and it only yielded 30 FPS with not many instances or substantial geometry. But you say you have to do the BSP tree manually?
I have some second thoughts about Unity because of the message thing and the web and iPhone things. I might be talking nonsense but man I want a PC robust game engine, plain and simple with straight forward output, something opposed to complicated, clogged and why not -- opposed to complex.
Sorry if I deviated from the topic. Anyway, I look forward to seeing if the same demo, any demo, is made in several engines.