This is a tricky one. I'm not sure musicians are generally in a better position to judge the quality of music. In fact my experience on SoundCloud is that musicians tend to form groups and help each other out so you may find the same thing will happen and you will just end up with those that have the best network rising to the top.
There are systems in place for SoundCloud where people take advantage of the ranking system by charging desperate musicians a fee to be reposted across large networks of accounts and as this site becomes more popular (and especially as there is money involved!) this will undoubtedly occur.
So the short answer is: I'm on the fence