I just bought one of the BLI E7s, and I was in such a hurry to test its sound capability out that I placed it on the rails without first checking the gauge of the wheels. That said, it's been operating through my Code 55 track (with #5 and #7 turnouts) without so much as a hiccup for a few days. It runs very well, and I have had zero tracking problems. I love it.
DFF