I'm curious if the type of coolant used might have some bearing (pardon the pun) on how long these pumps last.
Mine failed at 52,504 miles, according to my maintenance log. I had put silicate-free Prestone in at 38k. Best I could tell when I changed it, no one had done it before. It was like a pukish green sludge.
If it's leaking, even oil, I'd say if you're going to pull it out anyway, might as well replace for peace of mind.
One small piece of advice, and excuse the caps, but this is important:
BE CAREFUL WITH THE BLEED BOLT!!! It is very easy to strip the threads in the w/p cover, causing a slow leak that will drive you absolutely bonkers.
My fix for that was to use the cover from the old pump, and for good measure, to put some black RTV around the bolt, just in case. If I need to do another coolant dump, I'll just scrape it off and then replace when done.