Vandersteen, Coincident or Green Mountain

One word of caution. Even though I have not heard Vandersteens I have often seen them described as warm, and maybe a bit forgiving. My experience with Green Mountain speakers is that they are very neutral and revealing. I like this (I own a pair of Europas), but I can imagine that it will not appeal to all.

The Europas are very detailed, with great micro dynamics (and macro dynamics as good as a bookshelf could be expected to have) and they image like champs, but they could be fatiguing in a bright system or room.

So I'd recommend a demo before purchasing anything to replace the 3As.

I've owned the Super Eclipse III loudspeakers for about 18 months. My amplification comes from Audio Horizons TP 2.0B (tube preamp) and VTL MB-185 Signature monoblocks (tube amplifier). I use balanced connections. I have both analog and digital sources. Here are some thoughts that may be helpful to you.
Like you, I searched for excellent loudspeakers which are not dominating. My room is about the size of yours and, on the new extender feet, these loudspeakers provide big sound without big size. I replaced Wilson Sophias with the Super Eclipse IIIs. The Sophias are beautiful sounding speakers but are a little too much (physical size and forward sound) for my room.
The Super Eclipse IIIs take time to break in (preferably 200 hrs). They are full bodied, well balanced, and detailed speakers. They are so revealing that I was led to upgrade my preamp (from VTL 5.5 to the Audio Horizons TP 2.0B). Now, I would say, my VTL monoblocks are the weakest link in my audio chain. Whenever Audio Horizons introduces a monoblock, I will upgrade to it. I believe the Super Eclipse IIIs will be worthy of that future system.
Fully broken in and with the right equipment, the Super Eclipse IIIs deliver beautiful music. I have listened to them through Levinson solid state; I prefer tubes. The sensitivity and impedance specs of the Super Eclipse IIIs make them a very easy load to drive.
I've met and dealt with Israel Blume on several occasions. I've found him to be honorable and committed to excellence. I'm so impressed by the Super Eclipse IIIs that I will audition them to you if you are near my area (zip code 95818).
One last thought: my loudspeakers are in a natural finish - not so dark as the cherry finish advertised on the Coincident website. This lighter finish also contributes to their more comfortable presence in my listening room (known to others in my home as the living room).

Based on your description I strongly suggest you audition the Quatros as they will be a perfect fit for you. Once you've heard them compared with the other speakers you can make your own call. Let you ears do the buying!

Having owned speakers from all 3 lines, I would also highly recommend a quatro audition. They are less visually obtrusive (in fact, they are pretty cool looking) and they sonically surpass the 3A sig/2wq combo in every way.

Green Mountain Audio speakers are the most enjoyable speakers I have owned in 30 years. The music flows and the soundstage is huge. Of course, the best way is an audition. With no dealer close to you, I would not be surprised if Roy could arrange an audition for you with a return policy. It never hurts to ask. Speakers are so critical and all the BS in the world has disappointed many an audiophile and cost us all alot of money. I have not heard the Quatros and would want to do the same with those.
Good luck to you!