If you buy from GuideGear, they are ok, but make sure to keep reciepts! They do not take returns,(even on LIFETIME WARRENTY products ) without a reciept. Yeah, I know, it makes no sense, if it is lifetime, who cares when you bought it? And if it fails and you are the ONLY scource, who cares which store sold it, you still made it!
The only real difference between a good tracker and a bad tracker is observation. All the same data is present for both. The rest is understanding what you are seeing.