I have a Stealth 50 and am impressed with it. Clearly there are features that the Garmin has, that the Stealth does not, but you would expect that.
the unit performs well, the display is very good. I do not understand people talking about the "clunkieness" of holding down the mode button to save a trip, this is exactly the same as resetting the Garmin in order to save a ride track, just a different button.
my only complaint with theStealth actually is the proprietary cable/sled for downloading and charging. Of course this means you can't use any of your other cables, but the sled is what makes the whole unit water proof.
pluses and minuses.