Broke the refractometer back out for today's brew session. I let it set outside at the temperature I'd be using it at for awhile and then calibrated it (it was a little off). After reducing all of my brix readings by 4% it ended up being within 1-2 points of what my hydrometer was telling me. So I'm feeling better about the accuracy of it now. I'll be continuing to use both in parallel for awhile to see if it continues to track.