The ideal situation for performance and efficiency is warmer coolant temps, and colder intake air temps. There shouldn't be noticeable differences between 180 and 192/5F t'stats - either should work fine.
You should have enough capacity in the radiator to allow any temp t'stat to function properly - 160/180/195 - it shouldn't make any difference. For a street car, you shouldn't run without a t'stat; and if you run a racer without one, be sure you put a flow limiter in place of the stat. If you have any kind of winter at all, most folks find the 160 simply too low.
The ecu goes into closed loop as soon as the O2 sensors are hot enough to allow it do so. That usually occurs within 2 minutes of startup even on cold winter days for unheated sensors; for heated sensors, it can happen in as little as 15 seconds. Coolant temps aren't considered in that decision. So a low coolant temp (160 t'stat) won't inhibit closed loop operation - it's a myth. Heated O2 sensors were developed to allow O2 feedback as quickly after start up as possible to further manage emissions output. If temps get too high, the ecu will exit closed loop, and inject more fuel (rich mixture) to try and cool things down.
All the stuff about HP differences - well, the dynos are neither accurate enough, or repeatable enough to believe the 3, 4 Hp or ft-lb differences some have measured after 'icing' or cooling down. I have no doubt those numbers showed up. I just don't think you can trust them.
On a street car if you run electric fans, it's the higher of your fan control temps or your t'stat temp that will set engine operating temp in traffic assuming the system has enough radiator/fan to reject the heat. You can put a 160 t'stat in, but if your fan is on-off with thermal switches at 195-180 - then that's where you'll operate. Cruise to enough speed so that the fan's aren't needed, and then your op temp is set by the t'stat.
I use a 180 t'stat , and have my fans set to control to 187F. I measured my t'stat and it doesn't open until about 182, doesn't fully open til 184/5. So check your stuff if you're trying to control to specific temps. Just because it says '180' doesn't mean it's actually operating at 180.
Oh - the stuff about the coolant not staying in the radiator long enough with a 160 t'stat. Think about it. If the coolant's not staying the radiator long enough, the implication is that you're gonna be running warmer. If you put a 160 in, and the car's running at 160, then the coolant is staying in the radiator long enough to reject enough heat to get it to 160. If you put a 160 in, and it can't get down to 160, then the radiator doesn't have enough capacity to cool it that low. Remember, the radiator becomes less efficient at removing heat the cooler the t'stat is. That's because efficiency is a function of the difference in temperature between the air moving across the rad, and the coolant temp in the rad. The lower the coolant temp for a given ambient temp, the less heat the rad can reject. Said another way, it takes even more radiator capacity to reject the same amount of heat the lower the t'stat temp is. Don't confuse 'heat' and 'temp' - two different things. Lastly, if you put a 160 t'stat in, and the car is running at 140, then your t'stat is malfunctioning and not closing all the way, or your gauge/sender is either inaccurate or the sender is mis-located.