The standard tenor is the 19 fret instrument. The short scale (or neck) is a 17 fret instrument and as Shambles has indicated, it is quite popular amongst Irish players. This is because nearly all the music is played in the open position and the smaller instrument reduces the amount of stretching that the left hand has to do.

Jed, I have no idea which bands are currently using 5 string but I guess it will always be around as an accompanying instrument for Irish bands. The trouble with the 5 string is it is so difficult to play the jigs and reels and I have only ever heard 2 people play a 5 string in a style that resembles the more common plectrum tenor style.

Thinking of the five string, I have a tape somewhere called "The Melodic Clawhammer Banjo" with Ken Pearlman and others. This style seems well suited to jigs and reels and produces a good rythym which is what the bluegrass players normally seem to lack - they may keep time and play with great skill but IMO, they usually fail at expressing the Irish tunes.

Jon