Vertical arrays can't image vertically (how could they?). Since the main point of having two or more channels is to recreate better imaging, I'm lost as to why arrays show up anywhere (especially in HT).
Unless funds are unlimited, best to put the money into a much better single driver or mid/tweet if you're considering extended range drivers (quality over quantity). To be effective the array must have 10 to 20 drivers, so why not spend 10 to 20 times more on a better driver? If you research the cost of drivers in nearly any really high end speakers you'd be shocked.
If you're primarily after high sound pressure levels, shop for a speaker that is efficient or can handle lots of power and mate it to a big amp (watts are cheap nowadays).
Completely disagree with most everything here.
While it is true that there can be inherit diffusion in Line Arrays, it can be limited by a capable and thought out design.
Saying that you don't see a place for "line arrays," comes off as a little short sighted as well.
Line Arrays can provide better dynamics and peak output, with very little coloration(depending on the driver selection); then a point source speaker that is utilizing a few drivers mated to a woofer. Perfect for HT; and depending on how well the design extracts detail and resolution, excellent for music as well.
Also, while imaging might not be as pinpoint as your typical speaker, soundstaging can be greatly enhanced.
My GR Research Line Arrays extend to the walls and ceilings, with great depth.
Also, I'd disagree that watts are cheap as well.
Better designs cost more money period. Getting a lot of watts out of companies like Pass, Mcintosh, Manley, Vac, etc, etc, etc, costs money.