I bought a Hogwarts engine for $150 from a Forum member who put ERR in it. It runs fine, but the sound isn't good. He admitted as much before I bought it. Being an MTH guy who is only getting started in Lionel with a great used TMCC base and remote from you John, I don't know if it would behave any differently with a Legacy controller. My take on ERR is that it is more similar to TMCC than Legacy, but I may be wrong. I'll have to take a video of it and take the boiler off and post a photograph or two. Come to think of it, I am assuming it was a conventional engine, because why would he upgrade a LionChief and sell it for $150?
Kevin, Thank you for asking the initial question. It has caused me to delve into this a bit more and get the Hogwarts back off the shelf.