I know exactly what you mean MARZ06. I'm considering getting one myself. I kind of shopped around the other day, and think that the 178 degree would work best. I was going to get both the thermostat and the adjustable temp. sensor together. That way, the fans would kick on at around 200 or so to cool the engine down, instead of 230+.
I had the Hypertech chip and the 160 degree thermostat on my 92 conv., that works wonder. I love it.
Even though GM designed the engine to handle that kind of temperature. Just knowing that your car is taking that kind of heat torture, although it's not suppose to hurt the car, but it sure hurt me. I noticed the engine and the tranny making loud noise (sounded like the valvetrain) when the temperature is above 200 degree. It never make any noise when it's under 200 degree. Some people said that it's normal, and the noise is from the fuel injector. I don't care if it's normal or not, I don't like my car making noise. I think the engine last much longer running at a lower temp. too.
Just my 2 cents....