Love the idea! This is legitimately the coolest thing.
I'm curious why the seeding is ranked first by wins over ranked first by sum of scores? e.g. What if you were put up against 4 really strong composers, and lost 4 times but with very strong songs - is that fair compared to someone who was put up against 4 noobs and won easily with average songs? I get that score averages might be tilted slightly by how good/bad your opponent is, but I don't think the difference would be *that* much... (or would it?)
It feels to me that sorting by sum of scores would be the fairest way, plus maybe some sort of bonus for every win. But I have no doubt that you have probably considered this and have good rationale, so I'm interested to hear it =)
(Also, isn't 4 songs a lot just to get seeded? I mean in sexmodit mania, you only write 5 total songs, and isn't everyone exhausted by the end? =P)