I'm using the Ref 3.1s as my L & R channel, AGA AV Center, and Adiva Ti's for surrounds. The 3.1s and the AVs are completely different. Liken the AVs to a very good bookshelf speaker, though with the roll off around 80hz and a very high roll off on the top end. The 3.1s are a full range speaker, and you can bi-amp the front channels if you want to push them a bit lower.
Personally, I'm in love with my 3.1s. BUT, I wanted a full range speaker in my system. If you're looking for a sat sub the I think you'll be very happy with the AVs. If you looking for a full range, then you're going to love the Ref 3.1s. The AVs are identical to the AV center only they are built for vertical orientation instead of horizontal.
Hope this helps, let me know if you have any other questions, I've had my set up for almost 2 years now and am extremely happy with the speakers. Do I want to upgrade my amps, processors, every thing else because of them? Absolutely!! It's amazing what happens when you start putting quality pieces into your system...yeah, I've got the upgrade bug.
P.S. I should mention that I am in a similiar sized room as you, 11'7" wide, 22' long. You're using better electronics on the front end though and you'll notice a difference. Just noticed that you are listening to 70% music ration there...definately go with the Ref 3.1s then...that's my two cents.