My experience is that the GPS chip in the Curve 83xx is
very accurate but also
very weak. It loses the satellite far more quickly and easily than my regular GPS receivers do.
The slightest amount of cover will cause the satellites to be lost. It also takes a much longer time to acquire the satellite lock compared to a dedicated, recreational grade GPS receiver.
Having said that, while I wouldn't count on it routinely in the woods, I would certainly be glad to have it if I was lost in the woods. It would be better than nothing.