I listened to some of the pieces by Bill Brown. To me it sounds like typical Hollywood soundtrack à la John Williams. I'm sure it fits movies and such but I don't want that guy to do the soundtrack for Unreal. He's lacking uniqueness and style.
Brandon's music is so unique and characteristic. And, all the music for Unreal wasn't made using the most expensive gear (logic audio, samplers, hardware synths and stuff). It was made using a tracker and a few samps and instruments (the tracker term "instrument").
The Unreal 2 soundtrack will probably be in MP3 format, however all of us who have played Wheel of Time know how much it drained the hardware. If Unreal 2 is going to look absolutely stunning and make use of the latest 3D hardware technologies (such as T&L) it'd be wiser to use tracker modules for audio. The audio quality is great, the filesize is low and it doesn't require much computing power for playback.