I still contend that if you are running a large HP motor, mostly on the street, a large flex fan and good shroud are the way to go. It will move more air than most electric fans where you need it, Big improvement in street reliability ( no wires, relays, controllers, switches to contend with ), less than a quarter the cost, no additional burden on your existing electrical system. Trade off for the above will be a small amount of HP.
Most cars today run electric fans. They were designed from the ground up to run them and only have to deal with cooling engines that are less than 1/2 the HP we are working with. "Yesterdays" cars only used mechanical fans - what they were designed for.
IMO, it's really all about the application, as are many threads on this site. Both types have their +'s and -'s. Want reliability on the street, mechanical fan. Want that last bit of HP for the track, electrical.