lots of old style coolant header tanks have failed and split
whats the record for the replacement r53 style tank, a few shiny metal ones are available from several vendors but am i wasting my performance dollar if i have the r53 "improved" tank already

 

I had my original tank replaced under warranty, so far it's holding up fine. If it's not leaking, then there is no reason for going with an aftermarket tank unless you are going for a 'look'. The OEM tanks dont fail catastrophically, they begin to slowly seep. You should be able to catch this failure during regular checks under the hood. If the tank is leaking, replace it with an OEM or aftermarket tank. The choice is yours. I have not heard of aftermarket tanks failing (yet).