Not sure of the math is correct but 2160 cubic ft. 12x18x10? It connects to my kitchen which is separated by a counter. It wouldn't let me read your Review but after reading Andre Robinsons it kinda sold me on bookshelf speakers. For sub I was leaning towards an SVS PB-1000
Yeah, AVS has some odd rule about so many posts (10 or 15) before one can read reviews. Don't have a clue as to why. The short end is I gave the R5Bi's a 4 out of 5 (actually 4.4 out of 5).
Andrew is one of my favorite reviewers. It was his review that got me to go out and audition my Maggies. Five years later I was looking for quality bookshelf speakers and had no intention of buying the R5Bi's, because I felt a $225 pair of speakers couldn't sound very good, then I spotted Andrew's review. He hasn't steered me wrong yet. However, sound is subjective and there is no guarantee that you will like these speakers as much as I or Andrew. My advice is to order just two and test them out with and without a subwoofer (they need a subwoofer, but so do the others on your list). Well before your 30 days are up, you should know if you like them enough to keep them and look to fill out your system, or return them (return shipping is around $25).
Your room is considered a medium sized room, but since it is open to the kitchen, one needs to add that cubic footage as well. That will put you over 3,000 cu. ft., meaning a large room (for a subwoofer). While the PB-1000 is one of the best $500 subs around, you may need to up your budget and either get two, or go for a bigger sub (but try one first to see how it performs). Reaction Audio shows an S-15 (sealed sub with 15-driver) for $500 at their outlet store. I know one AVS member just purchased one (don't know if it was the only one), so check with Jeremy on the details.
http://reaction-audio.myshopify.com/collections/outlet This is a great deal. Also check the outlet store at SVS. Never know what may be lurking there.
Other subs to consider are the Outlaw Ultra-X12 @ $639 (shipping included for a limited time only), and the Rythmik LV12R @ $569 (includes shipping).