The OCZ Vanquisher proved to be a well-made inexpensive cooler in my tests. It is efficient, universal, simple to install, light, and very affordable. In other words, it’s got all the properties you expect to find in a product of its price. Still, I think the Vanquisher has got an even bigger potential because too much of its air flow it lost at the sides and bottom of the heatsink. I guess this is the reason, together with the use of a low-performance fan, why the Vanquisher was slightly less efficient than the Cooler Master Hyper TX2.
The OCZ Vendetta, on the contrary, boasts impressively high performance for its dimensions and price. Its performance can satisfy even a demanding overclocker that cannot afford a super-cooler. The cooler’s fan supporting PWM regulation, you can always select a comfortable mode while retaining high performance (this is also true for the Vanquisher). As for possible improvements, I guess the sides of the heatsink should be made blank while the base might be polished better. Perhaps this would provide the couple of degrees the Vendetta lacks to enter the league of super-coolers.