The $50-$70 bluetooth GPS units (51 channel, sub minute acquisition) are all better than the n810. Your earthmate probably is too.

The n810 isn't bad, but it is slow starting, only does 1Hz output (v.s. 5Hz on many newer units), and doesn't include WAAS/EGNOS for higher accuracy. The GPS chip is low power, but the rest of the n810 would be on draining the battery.

So although it is possible (to export the internal GPS via bluetooth, etc.), any existing GPS is likely to be better.