Thanks for the links. I didn't even realize there are *that* many choices. I use Arctic Silver 5 myself, I've had good results with it whenever I've been asked to "fine-tune" computers. I must admit I've been too lazy to do that for my own rig. No doubt it'd do good for the card. But temperature is much better now, after reducing OC and improving airflow, so I don't see any urgent need to tamper with the stock cooling.
As for the link I posted, I liked the tongue-in-cheek style of writing. And the main point was that some goop - almost any goop - is way better than no goop at all. Very evident in the tests you referred to, as well. The toothpaste comparison has some fun value to me, and it makes sense that evaporating goop does a decent job - as long there's something to vaporize.
I recently installed a new mobo, graphics card etc to a friend's computer, and I was a bit hamfisted when removing the old graphics card. I grabbed it by the heatsink, and there was an audible crack as the heatsink came loose. Well, the springs keep it in place and the card still works, but I think it's pretty obvious that whatever goop there is has gone dry a long time ago and should be replaced.
I don't think any decent thermal compound needs to be reapplied frequently, but I suppose it might do some good to reapply after a couple of years or so.