Welcome to GasSavers. I know this is a favorite "mod" of Saturns because they are vulnerable to overheating when sitting in stopped traffic. Would you be looking at this as a "safety valve" for grill blocks and such?
On my Saturn, I switched to a 195 Thermostat. I also have a "poor mans" manual fan switch. If my coolant reaches a temperature that makes me nervous, I turn on the AC for maybe 5 seconds max. That also turns on my electric fan and leaves it on for another 2 minutes. That 2 minutes brings my coolant back down to it's normal operating temperature. The trick may work for you too. Some people put at least a 5 minute gap in this action to be nice to their compressor.
I would think this would be largely a question of what you feel you want or need to accomplish. How much does it cost? Are you considering it because you don't feel the fan comes on soon enough, or to soon, or ? If a factory temperature switch works like it should, it shouldn't come on until the temperature is above the low end of warmed up. If it doesn't come on until the temp is to high, for your level of comfort, then this might be an alternative. Their certainly isn't any reason that what they have described wouldn't work and give you greater control. It's largely more a question of what your resources are and what your willing to spend.
My biggest issue is I don't like anything that can overheat the engine, because an overheated engine is a pretty major overhaul and it's a pain.
I also have a "poor mans" manual fan switch. If my coolant reaches a temperature that makes me nervous, I turn on the AC for maybe 5 seconds max. That also turns on my electric fan and leaves it on for another 2 minutes.
i think most cars might be like this. i'f found the my electric fan doesn't come on untill coolant temp is 220. untill i found this out i was doing like you, switching ac on and off to bring temps down when i first started playing with a grill block