Found this thread after a bit of searching and it deals with exactly my question.
2008 Tahoe LS, 5.3 Flex Fuel engine. 110k miles. Truck runs perfectly, coolant is good, levels are correct, and once it warms up the temp needle stays right at top dead center which says 210. I've run it with a scan tool that tells me the PCM is reporting 192-195 when warmed up. Heat is great, only concern is the same as was mentioned here. In cold weather (Midwest) it can take 15 minutes or so to reach full operating temp. I was considering replacing the thermostat, guess it couldn't hurt, but this being my first vehicle with the Vortec motor I'm still learning it's quirks, just didn't know if slow warmup was one of them.
Also, I"m a bit shocked at the price of a simple thermostat. $50+ for an OEM, $30 from any of the auto parts chains like O'Reilly or Advance. And they list theirs as 180 degree.
So, sorta picking the brains of the forum here...........