well in the last year I've clocked up around 14k miles on it in all sorts of weather, as you say if you want something 2 wheeled thats comfy, keeps you reasonably dry , has a reasonable turn of speed/performance, got plenty of storage room then you can't really go too wrong with a Pan (hey the Police were happy with them !!)
Add on to that the potential (depending on how you use your right wrist!!! ) of over 300 miles to a tankful.
Only reason I would change mine now would be if I could get/afford an ABS/TCS equipped one(ST1100 rather than the newer ST1300).
When the bike was in SBs (Exeter) for it's MOT the guy there was saying they had one in recently that had over 200k on the clock on still going strong!!!