With classical music tonal accuracy is very important. The biggest source of tonal distortion comes from room reflections. The speaker radiation pattern controls the reflections and has a lot to do the quality of the tone at your ear. While an omni does provide the illusion of a more spacious sound due to the increased room reflections, these reflections do affect tonal accuracy. You have to know if you prefer more or less room reflections mixed into your music cocktail. Everybody is different on that. Audiophiles in general do tend to prefer more room sound, but they mostly listen to pop genres where slight tonal distortion isn't as noticeable. I prefer less room sound so I use more directional speakers. I have not owned omnis, but I have heard them at shows, placed far from the walls and I never heard classical music on them. I have had several dipole speakers but doesn't work for me. I don't know of any omnidirectional speakers that have adequate dynamic range for symphonic music. For various reasons I tend to prefer traditional box speakers with wide-ish baffle.
