Compression
Two types of application for compression.
1. Single instrument is compressed
2. A mix of instruments is compressed.
In 1 a single band compressor works well.
In 2 there could be a variety of ways the instruments are mixed.
A. Similar instruments mixed into a bus.
For instance several guitars thrown together, Bass and Kick thrown together. In this application a single band compressor would be fine, and possibly be better than a multiband. What happens in this situation the louder of the two will dominate the mix, and this could work great with say kick and bass summing in the compressor. When the kick wacks it can sort of duck the bass.
B. Various instruments and voices are thrown togehter.
In this case the multiband will probably be better since you would probably not want the kick to duck the vocal when it wacks.
Phil