IMO, skip the E fan, it can become costly with little reward.
Rockauto has a motorcraft fan clutch for $80.
At speed, the mechanical fan uses very little power.
If this was your final mod and you have everything else you could buy, i'd say go for it, but to do it properly you are going to spend quite a bit if you want the setup to be future proof.
You could easily rack up a $400 bill doing an E fan, just to get a couple of hp.
Buy a fan clutch and spend the rest elsewhere.