The benefit of going to an electric fan is you don't have the HP loss inherant with the mechanical units. If electric fans serve no benefit, then modern cars would still be running mechanical fans.
I think modern cars come with the electric because they are transverse fwd, a little hard to do a mechanical fan there. If modern v8's are running them, I bet it's only for the .1mpg increase they may see on a dyno when they're trying to hit their CAFE standards.
To me, the added expense and effort to get that extra 7hp and .1 mpg isn't worth it. Not to mention the hacked, cobbled look I have seen some electric fan conversions have.
