I found 5500 and 7000 to be much the same. They can be a bit difficult to tame.

The 6000 is a finer design but very different. The key to understand, especially in a long room, is the side-firing bass units.

Bass is NOT omni-directional. Positioning and toe-in does matter (a lot).

5500/700 will project bass forwards down the long room.

6000 will project bass side-wards and the amount of toe-in used will determine

a) where any modes (+ and -) will occur, and
b) just how much bass energy is projected down the long axis of the room.

Will zero toe-in you just have to walk from back to front of the room to experience how much of that energy stays at the front.

With increasing toe-in you can feel that energy moving further into the room as the wall reflections get angled away from directly at the wall.

This all affects the balance of the sound and the listening experience.

All that said, you can find the sweetspot and really let them sing.

Rgds,
Nick