Does size matter?

I think that size does matter...sort of. It REALLY depends on a lot of factors: room size, amplification, acoustic treatments, and what type of speaker is being used.

There are a few small monitors that can reproduce a PERCEIVED approximation of the low-end you'd expect from one of the big boys. The Acoustic Energy AE-1 Signature is great, my favorite is any of the Westlake products, and I'm sure there are many others.

As you mentioned, in terms of space you really don't gain much, since the footprint is about the same. I think that the main advantage of small monitors is financial. Simply put, a nice pair of stands is often cheaper than paying for 2-3 more feet of finely crafted cabinets.

It really depends on what your goals are...

You're current speaker's really aren't THAT big. I went through the same thing & decided to stick with floorstanders. I don't like the idea of something that costs $3000 perched on a stand with a cord stretching across the room. Audio Physic makes some great small footprint, narrow profile floorstanding speaker's such as the spark, tempo III and virgo. I like those because they are light enough to slide into the room for critical listening.

If you room is really small - like 10x10 or less, I would probably head for SET amplifier land and some high eff monitors. There is a magic about those systems. No bass or weight, but that's a good thing in a small room. The most impressive monitor's I've heard are the reference 3a's.

Size does matter if only because you have a trade-off in speakers between 1)(small)Size, 2)effeciency and 3)bass. Mother nature will not let us have all three. If you go for small size you will give up one of the other two(at least). Smaller is likely to be less effecient and put a different load on your amp. Not better or worse, just different.

I remain,

clueless is quite accurate on the trade off on size and effeciency. small speakers = little bass, which i believe is the underpinning to good (read warm, realistic, etc) sound. the 8k speakers you refer to do not provide more bass. it may be better bass, but not more. also the absence of bass in a small speaker makes them easier to place in a difficult room. what the "8K" speakers can provide is the potential for transparency, i.e. the ability to hear all of the detail in your software w/out emphasis or lack thereof in any part of the frequency spectrum. if your electronics are not up to the level of the speakers then the high price of the speakers will have no value to you. small speakers can also work quite well with a sub in a difficult room as you can place the sub in a location which doesn't exacerbate the standing waves in the bass, so long as the sound of the mini's and the sub mesh.

Using smaller speakers in a small room is not a space saving issue. I have a small listening room (9' x 13') and have tried a couple of full range floorstanders. In a small room, these full rangers get "chocked", if you will. There isn't enough air space for the sound from them to bloom. I've had much better results running stand mounted 2 ways. Yes, I have given up low end slam, but I could make up for that with a properly placed sub. However, my stated view is biased as I regard midrange clarity and bloom and extended highs as more important than bone crushing bass.