There is a pretty noticeable difference between the Ottica's and Xtreme's and it's not just with the WAF as they stand 86 inches!! There is an added fullness to the sound from the additional 8 drivers that seems to be greater than the sum of 4 extra drivers, the fact that they barely break a sweat during large musical passages really helps define the inner detail that can sometimes get lost during increased spl's. There is also a deeper sound stage that also comes with having more drivers that can be quite addictive if you have the room to support them and in this regard the Ottica's are far easier to place within your average room. I own the first pair built, and my partner Jay and I build almost all of the flat packs sold, I run mine with a 4 stack of 12 inch GR subs and the combination will absolutely shock you with well recorded music. To give you another perspective, and i'm trying not to be too biased, I recently attended the Toronto Audio show, which I thought was excellent and the speakers that I felt had the closest signature to the Xtreme's, meaning with scale and size of presentation were from Grandinote, they were OBish line arrays and I believe that they cost 60K.
Hope that also helps,