I would say this really depends on where its taking the temperature and how well the fans work. Did they have any suggestions for you in the paperwork that came with your sniper?
If you have a temperature probe that's measuring the water temp in the engine, right at the thermostat, that's great for telling you how hot your engine is. But you know your thermostat will be opening at 180F and that water going to the radiator and then the thermostat closing. So now you have water closed up in the radiator, hopefully getting cooled down a bit, and then waiting to be pumped back into the motor when its needed. Using the water temp in the intake to control the cooling fans has a big drawback in that the water is separated. As the water in the radiator is cooling down, the water in your intake manifold is getting hotter.
Some people like to add a probe to the upper radiator hose, right when the hot water is coming in. The idea there is that the fans kick on as soon as there's water that needs to be cooled down. Downside is that your fans will be kicked on a lot more often. Even if you're doing 80mph down the freeway, hot water will be triggering the fans to come on.
Some people like to take the temperature at the bottom radiator hose. Right before the water is going into the engine. Reason being, you have a better idea of the actual temperature of the "cold" water as its going into the motor. But by this time, its really too late to do anything about it. You can't cool the water much more after you measured it, because its already leaving the radiator and back to the engine. Many factory cars these days use the temperature at the lower radiator hose to control the fans.
Personally, I think the most important part is the operating temperature of the engine. What you really care about is that its running at 195F or whatever number you decide. You can arrive at that same 195F engine temp using a 160F or a 180F temp trigger for your fans, all just depending on where you were measuring the temperature. And what works well in your car would be different that what works in mine, because we could have different radiators and different fans.
As far as my numbers, I'm running an aluminum radiator with dual 11" fans, rated for 1924 CFM total. 14lb radiator cap. 180 degree thermostat, on a mildly hopped up 351w. I stuck my temp probe dead center of the radiator. That way if I'm driving down the highway, the water has a chance to start cooling off without the fans and they won't come on if they aren't needed. Then I use an adjustable temp probe to dial it in and fine tune it so the car can sit there and idle at the correct temperature. Whatever value it ended up being that cut the fans on at the right time, I couldn't say for sure. I do have it so both of my fans kick on at the same time. They each have their own fuse and their own relay.
