Sometime in early '20 I replaced them with a set of the reissued Russiian Tung Sols and they have held up beautifully (however, I don't run them as hard and no mishaps involved).
@immatthewj If the amp really is class A, you do run them as hard. How loud you play the system has no bearing on the heat or tube life.
If the amp is class A1, if you were to put an Ammeter in series with the AC line, you'd find the current draw unchanged regardless if the amp is at idle or full power.