Sounds like I live up the street from you.
I've been running whole house fans for years. You will have a small problem with it in the form of insulation. That little louvered metal door is a lousy insulator.
On my latest place, I used one of the WWF's that has a pair of motorized insulated 'doors' that open when the fan is on and close when they're off. I also considered, but never tried, making a pair of insulated panels on lightly spring loaded hinges and attaching those to the top of a regular 24" fan so that when the fan goes on, the air blows the panels up and out of the way, and they close again when the fan goes off.
One thing I like about the WWF I bought is that it has a really low low setting, about 800-900 cfm. Nice when you want some fresh air flow but its a little cool out. I had to get up at 3am and shut the regular 2000+cfm models off on cooler nights.
Be fearful when others are greedy, and greedy when others are fearful. Just another form of "buy low, sell high" for those who have trouble with things. This rule is not universal. Do not buy a 1973 Pinto because everyone else is afraid of it.