My rule of thumb with PSUs is to let them get to the end of the warranty period and then pick up a new one.
No issue putting a PSU passed warranty into a spare machine or whatever that you won't miss if the PSU goes and takes your computer with it, but if you have a primary machine and especially if that primary machine is a source of income, keep that PSU in warranty.
Most Quality PSUs will give you something like 8/10/12 year warranties, which is a very reasonable amount of time to plunk down another $150-200 or whatever.