Sorry Eagle, but I have to disagree. I am currently running a 180* stat in my 4.0 and have been nothing but pleased with the results.
Does it cool better than it did with the 195*? No, of course not.
But, the engine runs as well as before with no apparent over-rich fuel mixture. Under the hood stays much cooler for 95% of your daily-driving, which can only help to extend the life of any hoses/wires in there. And, the few second buffer you mention is more like 45 sec or so, which is long enough to keep you under 210* on the gauge while pulling a load up a short hill.
Overall, it only works better for me. No disadvantages whatsoever and like I say, I stays a lot cooler most of the time.
Just don't expect a lower temp stat to cure your plugged radiator and you will be pleased with the results.
I agree with Eagle that the 160* would be a mistake. Forcing the Jeep to run in "warm up" mode all day would be rather foolish. But I say where the 180* is concerned, go for it.