Not all treadmills are created equal

I am convinced that all treadmills are not the same. One could argue that on a given day, any run could seem easier or more difficult than usual. But I'm starting to notice patterns. And as if running on a treadmill is not difficult enough, running on a "bad" one makes it that much worse.

Personally, I think I favor the LifeFitness models. I like to think they're accurate, as it seems like my perceived effort usually matches that of a run at the same pace outside. Though one negative, on the newer models they only read the mph and not the corresponding pace. Thank goodness I have years of treadmill experience, and some math skills, to figure that out. But I could do without the extra brain work that early in the morning.

I've also decided the Precor treadmills are plain evil. No matter what speed, what incline, I feel like I am running through mud. It always feels like I'm running a marathon when I work out on one of these treadmills. I mean, really, how is it possible that a 9:00 minute mile with 0% incline feels like I am running sprints up Summit Ave?

It's gotta be the treadmill, right?