An alternative way to check this, which should be very accurate is using the "Finds distance from home" table in your Project-GC profile, at the bottom of the list the average distance is diplayed. Mulitplying this distance by your total number of finds should give you an exact value (depending on exaclty how Project-GC determines this number).
It's not a checker, but still an easy and accurate way to do it without GSAK.
For example, our aveage distance is 566 km and we have 1797 finds according to Project-GC. 566 x 1797 = 1,017,102 km or 632,133 miles.