I know two people who post regularly to the monthly PDX Big Thread who have kids at Trillium. You might try asking your question in that tribal forum.
My son is at the
Village Free School, which is a democratic free school. If they became a charter school, they'd have to do standardized testing, which would go against the basic idea of the free schools (non-coercive, child-led). It's a private school, so there's tuition, but it's very low as private schools go...otherwise, my son wouldn't be there.
If it turns out that I can't continue to pay tuition at VFS, I'll definitely check out Trillium more closely. The one family I know well with a kid there really like it.