Last June I bought a Garmin Colorado. Like several other owners, I sometimes experienced drift when in woodland (on one occasion over 600ft). A GPS software upgrade (not a firmware upgrade) released around October or November appeared to sort the problem out and after that my Colorado seemed to be on a par with my 76CSx.
A couple of weeks ago I managed to damage my Colorado and sent it in for a replacement. Yesterday I got the replacement and it seems to be a brand new unit (serial number starts with 16911), loaded with 2.90 firmware and 2.90 GPS software.
Today I took it out for a test walk along with my 76CSx, in woods that I have previously been in with my old Colorado without incident.
Everything looked good for about 50 minutes to an hour, under various levels of canopy (and some open sky). Then I happened to look at the Colorado and noticed that it was saying accuracy was about 75ft, but the track was clearly a lot further off than that. I have previously mapped the path in question, and the 76CSx was on track.
The Colorado drifted further and further off course. Eventually I turned it off and back on and let it reaquire the satellites. At that point it was back on track and was OK on my walk back to the car.
I thought this was all sorted out now? I'm disappointed that this problem seems to have returned for me (even though it's on a different physical unit to before). I can't upgrade the firmware or GPS software because they are already up to date.