Well, I own a Flyonel Big Boy. And yes, when it was a K-Line economy O-Gauge model for those who wanted to own a Big Boy in the worst way, it was the worst way to own a Big Boy. No valve gear, an other glaring omissions made me think this is how Marx would do it. I know Marx has it's place but this one was spartan.
Lionel dressed it up as an S-Gauge model enough that I will say I am still glad I own it. Even over-sized as it is. It's a good looking beastie, and yes, I wouldn't pose it next to my Challenger, but it will always have a home in my collection. If Lionel or MTH brings out a proper one, I would buy that as well.