I'm with Moke...
The right music, right venue, close-ish location, omnis can rock (narrower split the closer I am, but I tend to never go much wider than a meter).
Bad room, poor location, etc. = cards or hypers (angle and split depending on specific situation).
Now when it comes to wind/outdoors, as someone who lives in SF (can you say always windy), I actually usually prefer cards if a good location and it's a typical PA recording, BUT... Omnis + the big ass sure windscreens = very good wind handling (even without low cut). So around these parts, I tend to fly omnis outdoors, LOL.
Also, if I'm matrixing, and I've got a good feeling about the quality of the SBD, omnis can be really nice for opening up and sweetening the SBD mix.