I know this thread is getting kind of old but YES! YES! (My same reaction to the Hudson Line and M7 EMUs).
An M6 can also be easily created with some changing of window border colors on the M4.
I am so ecstatic about this. As soon as I grab it I'm replacing that red stripe with a blue one and call it an M1/M3 as a repaint! (Even an LIRR one too with a yellow stripe!!!)
And since we all know Reppo's famous E33, there is no doubt that quality and accuracy will be spot-on.
*I do feel like an opportunity was missed with creating an official M3. All that is needed external-wise is a removable dynamic brake hump (on the roof) and no pantos.
"Let them be your reminder that we've combined the best of two railroads. But from now on, call us Penn Central."