After moving house last summer I switched from 3x5200s in the theater and 2x5500 in the living room, to 2x5200 there and 2x5500 + a 5200 (VC) in the theater. I was concerned at first that I would have to raise the 5200 the 6" required to match tweeter height, but it hasn't been an issue. I remember someone posting a comment from HH2 that Meridian stated height matching wasn't important since the ear is sensitive to horizontal positioning but not vertical.
I still want to play with raising the 5200s by 2 feet or so sometime, to make poor man's 8ks

Just to see if there is a bit more presence and sense of scale from height alone.