Yep, changed my 195 F out for a 180 F but also changed out for a bigger more efficient radiator too. Maybe a little more power if you drop it, but your radiator has to be big enough to control the maximum temp, because the stat only controls minimum temp. Your MPG may suffer a little. Better MPG at the higher temps because combustion is more efficient
I would verify the accuracy with a scan tool as mentioned, or with an infrared gun on the thermostat housing. If it's within a few degrees of 195, I wouldn't touch it. Your engine is tuned to run best at that temp, and your Suburban has plenty of radiator to keep things cool.
If you still have Death Cool in there, I would flush it out and go green.
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