I still use the first heater I ever had. It was an old style visitherm. I have had it for eleven years. It has been through every extreme (short of being thrown off of a moving vehicle ;P) and I currently use it in my 55gal brackish tank. I have never had a temperature fluctuation that I can recal. I am pretty sold on it. Not to mention, it has the temps on the heater itself and you don't have to guess what you are setting it at.
