Replace Stock Cooling Fan with Electric

Has anyone replaced their stock cooling fan with an electric cooling fan?
Have you realized any improvement in gas mileage or HP???

I have been eyeing up the flex a lite kit that bolts right in. Just kinda hard to smack down $400+. Electric fans are the route to go, I believe even the new suburbans/tahoes and such have them. It definatley frees up some power and less wear on the water pump. I had a 1989 Caprice 350 TBI, after I installed the electric fans it freed up enough power to chirp the tires shifting from 1st-2nd.

I've been looking at that same unit as a direct replacement for my stock fan, but wondered how reliable they were "aftermarket". Flex-lite appears to have a good product but wonted to get feedback from the auto people before taking the plunge. I've seen model #292 for as low as $338, free shipping.
Regards,
gb