Pretty hard to keep SMS interesting but I think the variations might be reading as a bit messy in areas because of the sound limitations. I definitely see where you were going, but I think they would have translated better with hi-q sounds. The picture I think you are painting in your mind doesn't seem to be communicating what you are thinking it is. Some of the sections seem to drag a bit, which I think is also a limitation of the sound canvas, it just makes your subtle variations get kind of lost. But as for the parts themselves, you have some absolutely classic sounding melodies, and really nice percussive beats.