Informal overall reliability survey / preventative maint?

[Boxtaboy]

Since my 01 is getting a little old in the tooth now, I've been trying to stay on top of all the regular maintenance items to prevent any downtime (as I use my car as a daily driver to work now). I'm currently at 59K miles, and have done the polyrib belt, replaced a worn motor mount, plugs, oil/filter change, brake pads/rotors, fuel filter, and coolant flush. Battery's at the end of it's 4th year, so may change that also. Lately, however, I've been thinking about items that haven't failed on me yet, but could leave me stranded, and whether or not to pre-emptively replace them to possibly help save me from having to get a tow. (ie. water pump, AOS).

Which leads me to my question- how many of you have ever been stranded in your Boxster, and if so, what was the culprit? Also, how many have had to replace their water pump, AOS, or coolant tank, and at what mileage, and do you think it is worthwhile to change them out prior to a problem occuring?

I'll start:
01 Boxster / 59k miles, haven't been stranded in it yet
- Cracked coolant tank replaced at 38k miles
- Water pump, clutch, and AOS are original and still working fine