Just picked up yesterday evening, unfortunately it has a CEL I have to sort out and she's a little rusty underneath but otherwise she seems fine.
EJ20X is a cheap JDM import engine that are dropped into turbo models that have been abused and blown up hard. EJ255/257's are hard to come by now so when people need to get something off the lot they get an open deck 20X and ship it. It's basically a car flipper engine. They can be equivalent in power to the 255, but CEL is probably because they didn't retune the ECU for it or left a sensor off and you're in for a doozy of a real repair to make it run "right" again. Gooooooood luck. You're going to need it. I personally would not have bought someone elses no-paperwork mystery swap with an active CEL.