Dead wrong.
190* opens later & closes sooner= hotter heat. Not exactly what you want in summer driving sitting in traffic. Even a 190* t-stat won't give you heat any quicker, just more consistant hotter heat on cold days.
As other have posted the thermostat temp rating has little effect on maximum(peak running) temperature. However running the engine without one can cause higher temps because the water flows throught the engine too quickly & doesn't allow for the necessary heat transfer from the engine into the water.
180* t-stat should be fine.
