I have one from Dieselsite that I won in a giveaway. Had it for 5 yrs with no problems. Change the filter once a yr. I get trash out of it every time. Its kind of one of those things that it cant hurt to have but most people dont ever think about it. All big trucks run them.
Mine mounts where the 2nd alternator goes and runs a hose around that T's into the heater core hose and then into the coolant resovoir. It works just like a bypass oil filter where it only runs 10% of the coolant through it at a time. It's also a great conversation piece when you open the hood...especially at the dealership