For what it's worth I'm someone that feels that while ball bearing wheels are great, I wouldn't consider them a real necessity. Generally speaking from my experience, if you start running long enough freight trains where a given engine has trouble pulling you are probably willing to spend the $ to have a second engine to pull them. Even with my 60 cars that get pulled up my pretty steep grade at the back of my house I still probably only really need two dash-9s to pull them. (One might pullem.)
Not saying you shouldn't get them if you want them, I just don't think they are really that necessary considering how much they can cost. Just depends on what you value and are trying to do.
I totally agree with you, for the price the Bachmann coal cars are hard to beat and they come with metal wheels.
I bought mine from St. Aubins for $25.00 each (in groups of 6) and with another $5 for Kadees, you just can't beat it the end product. It's what's allowed me to be able to get so many. I know they aren't the right scale for either of my 1:32 or 1:29 engines, but they look good enough to my eye.