If your clutch isn't slipping and they haven't been damaged during a change of clutch plates or from getting too hot, I say leave 'em in. Iv'e never had a spring fail but once I had a stud fail. The spring pushed into the side cover and it cored a hole right through the side cover. This was on a 73 Husky with magnisium cover. I found a place that welded it back on! I digress....A stiff clutch is going to cause more stress on your cable. It will fail sooner rather than later with the extra tension it is pulling on. I see no reason for stiff spings if the clutch isn't slipping. (I'm repeating my self) (self) oops!