There are many stereo bars out there with different design features, so it's hard to answer your question without knowing which bar(s) you are considering. In general, the biggest limitation will be how far apart you can place the mics for a spaced pair. For coincident and near-coincident positions, a stereo bar can be quite useful. Keep in mind that if you're getting omni mics, you may not get a wide stereo image when using them in xy or other close configurations.