1.5 years is too long? My early 2011 is super fast, and I hope it lasts a few more years.
Considering my Rev 1 lasted me close to 6 years (I'd say 5 good ones) I can't believe that a computer less than 2 years old can be considered "old" in any sense of the word, but if you just feel like throwing away money I guess that's your prerogative.