You'd probably get better results for free just by hanging out in the right communities and asking for feedback on your work. I don't know what those are for Sc

You'd probably get better results for free just by hanging out in the right communities and asking for feedback on your work. I don't know what those are for Schemes but they shouldn't be hard to find (and don't forget IRC). That also solves the problem of how to judge the reviewer - your reviewer is the community as a whole. If someone gives you bad advice, someone else is likely to correct it.