My understanding in CO is that public schools cannot "discriminate" based on test scores
There are public schools and programs in Denver Public Schools that require testing for entrance. I don't think it's a matter of discrimination.
My son is currently in a charter school in DPS that opened in August 2010...it's a great school but new schools can be chaotic. My son's classroom is fantastic but the school is still working out issues :-) If you choose a brand new school just be aware that the school will not be fully established when the doors open...it can take years before everything is stable.