I have one with Proto 2. I love it! one of the best locomotives i ever owned!
I have one as well and I also have a Lionel Legacy E6. The MTH is a far more detailed version and one of my favorite locomotives.
i'm not a PRR expert, but the MTH tender appears to be wrong, apparently made larger to hold the PS2 electronics. my favorite is still the Williams (Samhongsa) brass model from ~1987. no sound, but a beautiful model.
I have both a Lionel PRR E6 from 1989 or thereabouts and a MTH PRR E6 from several years ago. They both run well but the Lionel looks more like the real thing, The MTH is longer, leaner and definitely has the wrong tender as well as wrong proportions. But that is all to the good in my mind because the MTH resembles somewhat the old PRR E3 and the B&O version of the E3. The B&O had lots of PRR designed engines acquired when it was owned by the PRR. Odd-d
Lighthouse, my Lionel E6 is about 3 years old. The MTH is somewhat older.