I have two that have done 10,000 and 13,000 miles in six months (and that doesn't count the fact that they both travelled an additional 4,000 miles in my pocket to be dropped in the initial cache). Had I logged them here first in Australia, they'd be closer to 14K and 17K miles.
Both are free to roam rather than being jetted around the world in my pocket (the 13,000 went missing for 3 months, but made it back to circulation in September).
I know it's only small compared to a lot of trackables out there, but I'm happy with them.