I think speakers pointed down into the boat are the Bomb. IMO when you get moving the interior speakers get drowend out buy the wind and motor noise. Down fireing speakers fill the boat with sound. Most towers that have a swoop place the tower box in a position the all the sound from the tower speakers is shooting out of the boat and blasting behind you. So IMO you dont have to have it as loud to get the benifits from the tower box because the speakers are pointed right at you.
Here are some pic's of Tower boxe's with down firing speakers that Clay @ SoundIllusionsAudio.com did
BTW this design has been around for some time I didnt invent it, but I have been running it for like 4 years now. I see NOW tidal audio offer a down fire tower box listed on their website as the "industries first down fire tower box"