Old doesn't mean much. I know a couple of old sleds (71, 73, 75, 76, 78) still running hard. The only difference is that they are slower and a bit less comfortable the the new ones (less comfortable is a slight understatement). I would even say that they are more reliable than some newer sleds. When my cousin entered in an open class ability race with his stock everest 444, some people were laughing at him but when he won 1 st place, that changed very quickely, some of those 800 twins and tripple guys were kinda pissed that a 800$ sled could beat the s*#t out of a 12 000 $ sled.