I think we need to make a distinction between soundstage and imaging.
Soundstage is the overall width, depth, and height of the stereo image thrown
by the stereo pair. I *do* like the soundstage the best from omnidirectionals
because the soundstage stays stable relative to the 2 speakers even when you
move about the room. Unlike most forward-firing speakers, it doesn't
collapse when you move outside the width of the stereo pair. You can still
hear what both speakers are doing, but it's like if you're at a live concert and
you're sitting in one of the side sections. I was just auditioning a pair of nice
forward-firing speakers a few hours ago and I noticed that when I moved to
the left of the left speaker, the left speaker was all I could really hear. Not so
with omnis and bi-polars.
Many people distinguish imaging from soundstage, being that imaging is how
separate and holographic the individual images within the soundstage pop
into sonic focus. In other words, the soundstage defines how big the
soundfield is; imaging defines the elements within it. For imaging, definitely
you get more finite images with good panels or mini-monitors properly set up
and with you listening in the sweet spot. However, omnis and bipolars image
better than most people think they would. In fact, I find that omnis image to
about the degree I hear in live concerts. In a live concerti don't really hear
everybody's presence etched in 3D space as precisely as I do when sitting in
the sweet spot focused on mini-monitors.
However, given the omni/bipolar advantages in power response, stable,
realistic and scaling soundstage, and truth of timbre, I can comfortably give
up that last bit of imaging for all the other advantages I hear.
If you have a forward-firing pair of speakers and un uninterrupted home life
where you can consistently sit in the sweet spot, you might as well enjoy the
enhanced imaging of forward-firing speakers. However, since I'm often
puttering, cleaning, doing dishes, or typing on my laptop to the left of the left
speaker, I'm happier with omnis. And when I *do* finally settle into the sweet
spot for a focused listen, I'm plenty happy with what I hear.