I'm not an Aerial owner, but my brother is, and I've listened to his system at length with Aerial 6s and 8s. The 8s are a fantastic speaker with loads of bass energy, but it takes a lot of amp to keep them happy. If you've already dropped the coin for the Aerial sub, the 8s are probably overkill in a typical room.
Aerial 8B vs Aerial 7B
I am trying to decide between these, I already have the aerial sw12 sub, my room is average size, using a sunfire theater grand signature amp, would the 8 be overkill on base, looking for opinions from Aerial owners