It depends on the individual. Some people cannot handle not having the latest (and greatest) of anything.
I upgrade my Garmin watch every 2nd release - currently still have the 920xt. My wife does the same but on a different cycle - currently has the 935. So we always have the latest 2 versions within the house. Very happy with my 920xt and don't covet my wife's 935. Although the wife is always jealous during the periods that I have the latest.
I ride a Specialized Transition Pro (purchased in 2011) and use a Garmin Edge 800 bike computer (wife has an Edge 520). I do not feel like I am missing out on anything, so I'm not someone who has to have the latest
I upgrade my Garmin watch every 2nd release - currently still have the 920xt. My wife does the same but on a different cycle - currently has the 935. So we always have the latest 2 versions within the house. Very happy with my 920xt and don't covet my wife's 935. Although the wife is always jealous during the periods that I have the latest.
I ride a Specialized Transition Pro (purchased in 2011) and use a Garmin Edge 800 bike computer (wife has an Edge 520). I do not feel like I am missing out on anything, so I'm not someone who has to have the latest