I've had a Colorado since Dec 08 and I love the extra features and gadgets, especially the paperless Geocaching.  My only complaint is accuracy.  In short; it isn't.  It never settles down, it leads me far away from a cache and then back.  One time I almost tripped over a cache while following it 120 ft away, it settled there for a bit, then led me 120 ft back!  And all the while, my partner with a GPS60 was sitting there at the cache wondering what I was doing.  I sent a complaint to Garmin, but got no response.  What have others experienced that led to a factory repair? 

I've had a Colorado 300 since May '08 and love the paperless caching and being able to download cache info and upload my filed notes (in order.)  I have sent it back though several times, and have always gotten it back quickly.  First, the tracker ball fell out, and they sent me a new unit.  The next time, I had a computer type issue, where I suddenly couldn't retrieve my field notes.  I sent it back and they refurbished it, including new screen, for free.  Now I've had it for over a year, so I guess any future issues I'll have to pay for, but since the maze event in Rochester, whenever that was, I've had no problems (other than user ones.) 
I have not had problems with the signal - in fact several times I've had a signal when none of the other cachers in my group did.  When we went on the geoduffers golf course, I had better signal than just about everyone there (except for Marlin01 who seems to have a chip behind his left ear.)  You do need to hold the GPS flat though in order to get a good signal when closing in on the location. . .