Not all headphones change with burn in. My T1 really sounded bad out of the box and almost returned it after a week of buying it. DT250 on the other hand didn't change at all or very little. I don't know about Grados yet, I'm new with Grados (SR80i) and so far I'm impressed. I guess I like presentations leaning towards bright signature because it highlights details in mids and treble more than dark sound signature.
I have my eyes on SR325e as my next Grado.