My car doesn't seem to run as smoothly when it's sitting at N. I had a 180* t-stat in for a while, but had problems with it running to cold. It would sit about N or so, and not move. So I put the stock 192* back in.
I've had a 160 in my car for over three years with no problems. Look at it this way.......even if you do feel that it's to cold for your application, you can always swap a hotter t-stat back in less than 20 minutes.
I had a thread sorta on this same issue. There's a lot of debate on how cold is too cold. Theories on excess wear, more friction, sensors not in their operating range, etc. I have a 180° thermostat and a Fluidyne radiator, and the temp only climbs over "N" in bad traffic. If you're riding at around "N", you probably wouldn't notice the difference between a 160° and a 180°.
it really comes down to what temp the car ends up at in normal operation. some folks with fresh cooling systems (often upgraded) can run all day long at 5* over the stat rating, while some guys run a 160 to keep from hitting 220*.
the actual temps one runs at is more important to me.
Guys the stock temp gauges are pieces of crap. Just like you i had a 180 stat and a fluidyne and my gauge never went over the N unless i was really hammering a lot or in gridlock. I thought wow this radiator is awesome i must be running sooo cool. Then i decided to find out for real with my Autometer water temp gauge. Your stock fans dont even come on until 210 degrees so when your not moving your car usually heats up until that area. Even with my fluidyne 180 stat and using my tweecer to set my fan temps to come on at 185 i usually run at around 183-191 degrees depending, so trust me your car is not getting tooo cold at all. Also dont get a 160 your car has no reason to run that cold, its just not really worth it. 180 is fine for most cars. Remember guys the Tstat is the lowest your engine can go, so if you have a 180 you are probably in the 190 range.