I am glad more and more that I got the Nike + system. Especially after running on some dodgy treadmills while traveling in January. A few were way off, including one older Precor in the UK. I had it up at 12mph while the Nike+ was reading about 7mph. After so many days of that, I started to doubt the Nike+ a bit, especially when I ran on a Life Fitness model in the same club.
However when I got to Heathrow and ran on a very new Life Fitness model with a TV, it matched up almost exactly with the Nike +, which is what the treadmill at home does. I calibrated it one day before my trip, and then checked it again when I got home and sure enough it was very close to reading the same distances and pace.
At this point in my life, I know I can run a 10-11 minute mile easily, under most conditions, and so if I just make sure I run for at least that long I can maintain my streak. However I'll slow up at some point and I do try to gauge how hard I'm pushing myself across days by watching distances. There are days that I know I need to just do a mile to ease up on the body, and there are days I want to push farther, but not too far since I'm not taking days off.
It's a balance that the Nike+ system helps with.
Plus I don't have to remember times and distances now. They're stored on the Nano and at nikeplus.com.