I've been avoiding this thread due to all the happy and optimistic posts that it started out with. I don't care to argue online with people who are already satisfied and secure in their knowledge.
I totally agree with Rick and the others who said to replace it as preventative maintenance. Like an IMS failure, a catastrophic water pump failure is statistically unlikely to happen to your car. Like an IMS failure, a catastrophic water pump failure can ruin your engine. It is a lot easier and less expensive to replace a water pump regularly than it is to replace an IMS. Why not do it?
My experience with it is a little more extreme than most cases, but you can read about plenty of problems on Rennlist and other sites if you look around. I bought a cheap Boxster that had lots of issues and had probably been using dirty pond water for coolant. The water pump looked like this when I replaced it:
The engine did not overheat, but it seemed to have a hot-spot in the cooling passages that would build pressure and cause coolant to vent out the over-pressure valve in the tank. I tried various means of flushing the engine, short of disassembly and replaced the oil cooler. It didn't work. In the end, I decided to push the engine to failure rather than put more time and money into it. It has now reached that state and I'm pretty sure it has a cracked head.