Are temperature controlled fans any good?

I want to put some arctic cooler pro 12 thermal control fans in my PC (ones without the fan guard) but I hear that the fan stays at 500 rpm and does not speed up until 32 degrees C. Is this safe? This review http://www.bjorn3d.com/read.php?cID=1668&pageID=7512 says the fan's low cfm causes the ambient temp inside the case to be higher than normal.

I will be overclocking but my main concern here is noise cancellation. I intend to put a red LED 80mm fan on the case very close to the heatsink. This will take in air. Of the he 120mm fans I buy, one will exhaust from the back and one will intake from the front. My video card has a vapour x fan and my core 2 quad for now has stock cooling. I hope this helps.