I'm going to step back a few pages and mention that I have a 180 degree thermostat in my V8 swapped truck. It has new hoses, Duff radiator, new high flow water pump. I was having problems with it getting hot while driving up long hills - not necessarily overheating, but it would sit at 195 all day and then quickly spike up to 220, 230, 240 as I started up a hill. I had tried several thermostats and replaced the water pump to improve things and not much helped.
The 180 degree thermostat has actually made a pretty remarkable difference. It still gets warm on occasion on really hot days but definitely not like before - my theory is that while it does usually run at around 190-200 degrees during normal driving, it opens sooner thus regulating the water temp a little better. It also allows it to flow water through the radiator longer than it normally would.
In short they will certainly not fix overheating problems but in my case it has helped moderate engine temp in very specific situations.
Heater still sucks, has sucked always, first gen heaters are just terrible all the way around.