By his music alone, I'd guess EIE. I personally don't like his non-soundtrack music, as I find it pretentious and boring. But his soundtracks (Blade Runner, Alexander, 1492: Conquest of Paradise) I find to be fucking amazing. They're full of loud, exciting and operatic tunes.
However, if you look and listen to him, he doesn't sound or look like a Beta at all. In fact, he seems more a) Gamma, b) LIE and c) uncannily like Expat, especially when you watch the video. Si PoLR is blatent to me (check out his hair).