I think pretty much everyone has seen the "aftermath" of the battle.
Personally I'd sacrifice a little of the "shock" factor to see a row of over 30 ships get their asses whooped by a single Borg cube. Can you imagine 10 mins of just pure insane fighting, with the Borg swatting the helpless Federation ships like tiny fruitflies?
Then afterward, show the Enterprise pass thru a "very detailed" version of the aftermath. I think it would still be quite shocking.
What TNG needs really is to spice up it's already current FX shots (make ship movements longer, more detailed, better backgrounds, more camera/panning/zooming, etc) AND it needs to add "implied" scenes (like the 20 ships that were going to form a "Tackyon Grid", I think we saw 3 ships of that armada? Show the full 20 this time. And for the scene with Data uncovering the Romulan ship, show a huge extended scene of the ship firing torpedoes and destabilizing the cloak, and have the Warbird pull these crazy maneubers to get out of dodge, and get it's ass back to Romulan space.
This is what to me would make me buy the entire TNG collection (You hear that Paramount????? Redo all the FX shots in TNG a'la TOS': "Doomsday Machine" and my wallet automatically becomes yours!!!!!
If they do as you say, it won't be quite shocking, it'll be quite boring... we'll have wasted 10 minutes of screen time to basically seeing 40 ships go down without a prayer of a chnace... so if we know that's going on, why would we want to sit through it? We did that during "First Contact"... we don't have to do it again. Besides, the Dominion War gave us enough "epic-scale, hopeless battles" to sit through.
I agree, that from a dramatic standpoint, it totally ruins the impact of the Enterprise going through the debris field, if they also show the battle. That scene was written purely for visual and emotional impact... to show us suddenly, and without preparation, just how much devastation the Borg were capable of visiting upon us... with ONE ship!