The newer e-trex's have a different chipset and are much improved over the older ones.
Prior to the two I have now, I had the old blue etrex legend.
It often lost signal in heavy cover, but seldom, if ever, loose signal on either of the two I've mentioned.
However, I still, take a paper map and compass when riding in the wilderness area or National forest.
For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.