I sold my eD A2-300 and am in the same boat as the OP so I have really been watching this thread.
I have a large entertainment room in the basement that is open to a bar area and playroom. About 5500 cubic square feet total. I will be sitting about 11ft from the subwoofer it have flexibility along the front and side wall (side wall being next to the main seating). I currently have a PA-150 in the front right hand corner of the room and this is where the new main sub would go (PA-150 would either be relegated for the back of the room or sold).
I am really leaning towards the Epic Empire. I spoke to Chad and he is a great guy. Gave me some good advice and was not a BD salesman like you sometimes find. He told me if I bought one Empire, and decided to buy another down the road, he would honor the dual Empire discount.
I am not looking for earth shattering bass. I have three young kids and rarely get a chance to watch movies alone in the house and play at reference levels.
That said, I may be able to stretch for the HSU 15, really like the company, and like the options of using two open ports, one open port, and some of the other features. The Rythmik FV15 is also enticing, but would most likely be too big of a stretch. For just a little more I could add a second Empire down the road.
Plan on ordering either this weekend or early next week, and may be overanalyzing everything
Pretty sure I would be happy with any of these three subs but I am just trying to figure out if the HSU is worth extra money. From my understanding the Empire will actually extend lower and may have more midbass punch.