We get requests on a pretty regular basis for a GPS system to help keep up with a pet in an urban setting. They want something that will help them find a dog that gets out of it's fence and gets lost. The dog would wear the collar in the yard and if he digs out or climbs the fence, you would use the system to track him down.
The Astro really isn't designed for this but the new 2 minute update rate just might make the DC 40 a viable option for locating a pet that gets out of your yard or your containment area.
The issue with the earlier versions was lack of battery life. The DC 40 now has a 48 hour option. If you wanted to use it in this mode to help find a lost pet, it would do a pretty good job. The concern is that you would really need to charge the collar daily or every other day at the latest. That way you would still have some charge left if your dog gets out.
It isn't the ideal product for this job but I would rather have it over all the Dog Location GPS Systems on the market today. They require a monthly service fee and are not waterproof. Our testing of these products has been pretty unimpressive so far.