In this case, I agree its an E-8. My general rule is if no weird weather situation and the outfielder camps under the ball or appears to have plenty of time to get to the ball, but doesn't make the catch, I'll call it an E.
How about the case where there is blinding sun, the outfielder has a glove up and is tracking the ball, but loses it, bends away and the ball drops. I've always considered this case 'more than ordinary effort' and scored those plays as hits (even if the fielder gets a glove on it or is hit by the ball).
Same with a 40 mph wind on a pop up to the infield. If the ball is being blown all over the field on a windy day, I've scored these as hits on rare occasion as 40 mph winds don't happen every day.
I will always score the routine pop-up where three guys let it drop between them as an E, its just difficult sometimes to decide who its on... I normally will give it to the player who's zone its in unless another player has been calling wildly and then gives up, at which point I'll give the error to that player.
On the pop up where the infield is back, the ball is hit right behind the pitcher's mound, all players sprint in but nobody gets to the ball, its a hit.
There are so many variables to consider...