I have two hydrometers. One reads .002 high, the other .002 low. I marked each one and compensate for the error.
I love my refractometer when doing AG batches. Once the batch is in the fermenter, however, I put it away in its zippered pouch and use the hydrometers. Even with the alcohol correction calculations, I'm not confident that I can get an accurate reading with the refractometer.
Good Temp Control -----> Happy Yeast ------> Tasty Brew