I think if I had my first novel complete I might enter it. But (and you just knew there would be one) the question would be, if you don't make the cut, and you rewrite the thing, would you still be considered "rejected" by these houses (just a note, when you're book is rejected by one Tor editor, the book is rejected by them all, which is why an agent is nice, they should know which editor to send it to)? And then, because I've seen it elsewhere, and as a former musician, you want your royalties based on "gross" sales, not net (even if it adjusts the percentage down to 7% or so). It's very easy to show a highly successful book/record that didn't make a profit (get to "net"). Also, once the book earns out the cost of production and promotion, unless it's a runaway, there's little incentive to print more books. The publisher would have to see good demand to do that (witness Scalzi's "Coffee Shop" book).