When I bought my boat I put in a set of Globe impellers (1997).
I started getting nervous in 2002, but temps were right, water flow was right, etc. Couldn't stand it any longer in 2003. Pulled the Globe impellers out.
They looked just like the day I put them in. In fact, If I hadn't been Careful to keep the new set of Globes separate from the Old ones, I probably would have mistakenly put the Old ones back.
Oh, approx 500 hrs on each engine. (8V71TI's)
OldHatt45
PS: The second set works as good (so far) as the first.