"One thing I felt was that most speakers in the 600-1200 range weren't worth upgrading too. You've gotta go higher, to hear a big difference."
While I feel that this is true, it is just important to find a pair that you are able to get comfortable/familiar with, more so than anything else when in this price range. I recently did quite a bit of research/listening in the $800 to $1,200 range. A lot of depends on your room, ears, etc. I know of a mix engineer who for years worked on a pair of Behringer Truths and some of his work has been all over the radio. He was able to compensate for the flaws of the speakers in his mind. I'm not advising them
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, but just pointing out that it really depends on a lot of different factors. He claimed they were the least stressful on his ears when doing 4-5 hour sessions. But in the last six months, many manufacturers have started offering pretty amazing sound for under $1,500.
That being said, with monitors, yes, we want truth
and accuracy. But at the same time we want our mixes to translate well. Either, let alone both of these were pretty hard to find for under even $3000 and without a pro-treated room until recently.
While PDP's list above of manufacturers all make great stuff, for me it came down to the HS's and the above mentioned Adams. I had a set of Tannoy 501A's that were borrowed and I surely was not going to even bother trying to work on my M-Audio DX4's. I knew that the HS's were not going to be NS10's, but for the money, and my happiness regarding pretty much anything I've owned that was made by Yama in the past, I decided to bring home a pair of HS80's. (I also tried some of the new Sonodyne's, a pair of JBL 4328's, and Event 20/20's. I knew I needed at least a 6" woofer; I've found in the past that anything smaller isn't going to give me what I need on the low end without a sub. I had them for three days and the opportunity came up to try bring home a set of the Adams. I was amazed at the flatness of the sound. In fact, it scared me; I thought that with the ribbon tweeter that perhaps they were tricking me somehow. Being old fashioned, I passed on them and then proceeded to bring home a pair of HS50's and the HS10 subwoofer. (I have a rich acquaintance that is a true audiophile who allowed me try most of the aforementioned, too bad he is obsessed with Skinny Puppy
).
I want to mention subwoofers here since there seems to be a misconception regarding them here. When you use a sub, there is a cut-off filter switch for a HPF that is adjustable to dial in how much bass you want in the mains and so you can fine tune it to your room/set-up. It does not just add another layer of sound to your main monitors. Yes, you can set it to "kill" and your mixes will translate bass heavy on other systems but when tuned properly, it allows the bottom end to be truer and you can actually hear what is going on, allowing your mains a bit more headroom, so to speak.
I often track in a nice studio and often finalize mixes there and since I've had my new set-up, I rarely have had to fix any issues after setting a mix up at home. The speakers I check my work on include a $20,000 set of Tannoys, NS10's, some old amazing Focals, etc.
I ended up keeping the HS80's AND the HS10 sub and have been very happy so far (six months in). I work nearly everyday on them. For the money, I don't believe there is a better monitor out there. I kept the sub because my room is 1,700 sq-ft and with my HS80's, I have a wonderful clean bottom end (I actually use the filter on the sub to shelve the bass a bit as the room is so big and I still need to build bass traps) when working and I'm still get excited just working on them.
For a 13x13 room, I think you would be fine with a set of HS50's and the sub, or a pair of the HS80's. It's vital to be able to hear the bottom end; educated guessing will/can get you by, but with the cost of the Yamaha's, Why Not? Both are very flat from 300 up and stay that way all the way up to around 95db (at least). Go for the 80's, or get the 50's with the sub.
FWIW, If I could (and probably eventually will) I would get the Adams as a second pair. They would perfect to have to work with for near field/general scrubbing/editing and then have the Yamaha's to double check on and visa-versa. But I would do with the Yama's to start with. I've noticed that while the GC have actually raised the price on the HS80's, most online stores are now selling them for $6-630 a pair and the HS50's for $400 a pair. Plus I like the few switches the Yama's have for adjusting them to your room. As I said, for the money, I don't think there are anything better out there. right now. And being Yamaha's, they are built rock-solid.
Speakers I absolutely hated during my testing: KRK's, Alesis M1's, and the Mackie 824's.
The Nuemann KH120's were decent but the Yama's have a bit more power and more features.
More suggestion please!! 
