I have always wondered about compression and using it in a live setting. I have read information on what compression does to your signal, but what application would it be suited for?

Also im looking at the nano soul preacher, any thoughts?
Remember that funk compression and sustain-compression proper aren't exactly the same thing, we're talking about the latter here.

Compression is used so that it's easier to hear the nuances of the music in a loud setting, as well as evening out the volume of each note to a certain extent. Also it makes the music seem louder, without an actual decibel increase. Think highly-commercial pop songs.

No guitar pedal will match the sort of compression PA guys use, but if you want sustain then the soul preacher looks good. Haven't ever tried out stombox compressors though.
Quote by Tombe
With pedals you can throw your guitar down for an impromptu pedal drone solo, whereas if you did that on a rack it would just look like you were programming your washing machine.