Hi, one of my basses is tuned in 5ths. It is a medium scale Warwick (32.5 inch or so). Which makes it a bit easier. 30" would be even better........
It is fun. 3 string cords have the minor or major 3rd in the top string (technically it is a 10, for it is one octave higher). For instance, an E-chord would be E, B, G#. On a normal 4-string such a chord would be E, G#, B. The nice thing is that these high 3rd give a clear flavour. (sorry, I'm from Holland, hope my English is good enough!)
4 string chords are also nice. That might be E, G#, B, D. So in this case the 7th is in the top string. Again, the note that gives flavour is best heard.
A setback is that chromatical (ish) bass lines are harder. A common blues line E, G, G#, A, B is harder to play. If you jump octaves it's easier, but those bass lines sound different.
I play more melodic stuff on the 5th tuned bass. Irish tunes, country tunes, it's all easier. So it tends more to the 'folk' side of things AND to the prog/experimental/alternative side. Think TOOL for instance, or 16Horsepower. I use more doublestops. I prefer to play this bass with a pick, more "guitar like" so to speak. With a pick it sounds clearer and 3 or 4 string cords are easier to play.
More traditional 'groove' music is easier on a normal tuned bass. You don't want jumping melodies there, but simple lines "played in the bucket'. Top 40, or cover bands, is also easier played in normal tuning (you are copying someone, so use the original tuning...) My normal tuned basses I play fingerstyle, which gives me more control over timing and volume
OTOH, I found that Jamerson Motown lines are good to play on a 5th tunings bass, maybe because he likes octave jumps ? One bassist who uses 5th tunings is the french player Yannick Top. He can be heard on the classic "Il jouait du piano au debout" by France Gall. Very nice groovy bass line (one of my favourites actually) :-) http://youtu.be/fOWmw3Qc21c I read that Yannick started on cello and kept that tuning. He seems to have no problems on the bass guitar!