I know it's not a commercial, I was just pulling your leg
. After reading for like hundreds of small speaker that they sound bigger than they are, I simply started seeing this as normal. They probably don't sound one iota bigger than they are. Perhaps only if compared to what a 6 liter speaker could do in 70'. Today's speakers might seem bigger than they are, but it's the new standard, nothing more. They're exactly as big as a contemporary 6 liter speaker is.
And I haven't heard a small speaker being as big as a large speaker. Not yet.
What I'm trying to say is that I'm seriously starting to doubt that 4" mid will suffice. You can't fix or help/assist your mids with a sub. Get three 12" subs and you stull have 4" mids. And this is something I'll try to investigate a little bit. I'll try to listen to as much large mid driver bookshelves as I can. I have to see what's there.
I'm not completely sure about the dynamic range. Since you show a lot of interest for this topic, I'd really like you to hear LS50's when they're loud. They are suppose to be able to do everything you say; go loud, not distort, cover the highs and the lows and the loud and quite parts. But close your eyes, it's a small sound. I perceive it as beautiful, accurate, fast-paced with astonishing low end not the slightest fatiguing highs, but small sound.
So I'm guessing it's not the dynamic range. I still may be wrong. Perhaps the impression of the size of the sound stage goes under the dynamic range as well.
I'm really curious about how would a 2.2 music mainly, bookshelves system sound that has larger drivers. Subs 12" min. but perhaps 14" and a min. of 8" mids.