I have one on my card right now. Havent had any problems with the cooler. I did however have a problem fitting it into my case. One of the memory slots gets in the way IF you have a chip in the slot.
You can increase the effectiveness of the VF-1000/RHS88 if you rip out the HORRIBLE Zalman fan and strap on 2x quiet 80mm fans - in my case, 2x 80mm Nexus fans (both at 100% speed). Takes up a full 4-slots, though. This setup keeps my heavily-OCed 8800GTS640 at 64C at full load (which is good for an 8800GTS640) and its exponentially quieter than the stock Zalman fan at 100%.