Matthew Starner talks about using tracks with the church praise band:
Generally speaking, I’m not in favor of replacing key instruments digitally. Our normal team consists of drums, bass, electric guitar and keyboard. Even if one of them were missing, I wouldn’t be comfortable replacing any of them with digital musicians because they’re too important. However, this does depend largely on your circumstances. If you’re just starting out and you have only a guitar player and vocalist (and they’re both you) then you’re going to have to find a way to enhance your sound. There are options for this such as Worship Backing Band.