I don't think it's about replacing one with the other. The discussion is smart watch/activity band/whatever in addition to a regular watch. Of course a tech gadget will be a cost on top of the other watch(es). Personally I don't upgrade my tech just because a newer, better version is out. I tend to keep using stuff until it (a) completely dies; (b) is on its last legs and I fear being without it for even a few days; or (c) key functionality breaks. So probably more than 2 years for me.