I have a Kinwin -3000 and am fairly happy with it. It brought the CPU temp down to 110F under full load (from 125F), with the unit mounted externally. It's a pretty warm room it's in too.
My main problem with it is that the pump is weak. The unit comes with a small water flow indicator, which stopped spinning after 2 weeks. I opened the unit to see if the pump is still working, and it is, although I noticed the temps have gone up by about 4F. I thought about RMAing it, but decided it's too much of a pain in the a$$ to take it all apart again. My plan is to add an external pump, which will run me about $70.00, but it will allow me to add additional cooling plates. The radiator it comes with seems to be very good.