Answering the original question, a 5-string is a great instrument so long as you know how it works. I write a lot of stuff, and the range of the fiddle is important for that. I can't think of any negatives (apart from 5 new strings cost more that 4), but there are a lot of things to be aware of, if you already play a 4-string. If you are serious about a 5-string, read through this and decide if any of this puts you off. If not, then go for it! Or at least, try one out, for a decent length of time..

Here are some observations I've made, after seeing others buy 5-strings. I'm not trying to put anyone off, really I'm not. Just raising awareness.

What follows is my post from a discussion on another forum :

I also think a 5-string is an instrument in it's own right. If you have a need to play across its full tonal range (which I do), you simply cannot do that on a standard 4-string. If you start trying to draw parallels / comparisons to the standard violin / standard viola, it's pointless. It has the note range of both, but that's where the similarity ends. To me it would be pointless getting one just because it has an extra string. I know several people who bought a 5-string based on this thinking :

"A low C string is nice to have ..."
"I can play in the tonal range of both a violin and viola! How cool ! ..."
"That means I can play all my tunes down a fifth if I want to! Brilliant ! ...That settles it. I'm getting one!"

Now here's what actually happens :

They still play pretty much the same stuff they always did, eg Irish trad, Amercan old-time or English folk. They hardly ever need to use the low C, except for maybe as the last (harmony) note to finish off a tune in D or C.

Playing in sessions has no advantage either - not many tunes are played in C (so you won't be using your standard G fingering, down a fifth). Few people are interested in playing sets down a fifth (eg set in A played in D, using the same fingerings). They like A because it's loud and bright, so why drop down to D, where all the other 750,000 tunes are?

So, we're pretty much back to using 4 strings again. And, ho-hum, the old story repeats itself - only ever playing 4 strings on a 5-string has its disadvantages. The body will usually be slightly bigger, and heavier. The neck will be wider. The strings will be closer together. You can't hit hard on your low G with the freedom you have on your 4-string - it's easy to hit the low C by mistake. If you've decided to play some of your tunes a fifth down, you don't have the same freedom of bowing a hard open A, without accidently hitting the open E. The bowing plane is quite different, and it's something you need to get used to. You'd be surprised just how few tunes suit being dropped down a fifth ...

So, they sell the 5-string and go back to their original instrument (if they haven't already sold it).

There are thousands of standard fiddles out there, but relatively few 5-ers, and there are a few dogs going around, too, which doesn't help it's reputation

Hope this helps!

Mr Jim