Cap'n Charlie, thanks a lot - that's perfect, and pretty well explains everything...
-I'd bet your right about there being other transmitters, but that is definitely contrary to what the instructions say - they make no such mention of other transmitters, and say or imply basically, if you're more than 600 or so miles from Ft. Collins, or even less if in the mountains, then you're out of luck.
-On the altimeter, that makes perfect sense to just calibrate it each use with a known altitude, and that it could be very accurate measuring relative to the pressure measurement taken at the time that you calibrate the known elevation. I still don't see though, how it could have any accuracy at all really, without such a known-alt calibration, but it doesn't matter since following that procedure will work perfectly for me. I can use the GPS to get the known points (deer camp(s)).
The most deviation I've experienced is about 40', but understand, this wasn't at high altitudes like, say, 8000'. It's not precision, but it's usable.
Good enough for my purposes.
-You're right, it's a rough instrument, and the kentucky windage you mention is gonna be plenty close enough for my purposes, to get out of the woods in the dark or in weather. You're exactly right, if it's a long track involving potential danger, it's gonna be GPS as the primary tool, and this only as a secondary/backup. I guess I was making too much of the declination thing - it ain't off by that much where I live.