I've been using the dh-t660 for about 8K miles in all sorts of weather and all sorts of terrain ( road, MUP, gravel, dirt, etc. ) and haven't had any issues that would make me think twice about getting on again. The only slightly annoying thing is that I get a distinct vibration at around 16-18 MPH, but according to a Google search that's common.
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Knows the weight of my bike to the nearest 10 pounds.