I'm not a fan of using a GPS electronic compass (Geko 301) because they use a lot of battery. Much better IMO to watch the compass course as you are walking and use that as a virtual compass. Comparing that course with a mag compass should give you the correct declination to apply if you aren't sure.

IMO the strongest attribute of the Geko family is size; they're small enough to EDC (smaller than many cellphones) but they can give a precise location to a 911 operator if the situation requires.