In another thread Mark said that a certain guitar would benefit from a bone saddle.

I've seen many reviews where the benefits of a bone nut & saddle on an acoustic are discussed.

What are Fretter's opinions about changing a nut & saddle to bone?

1) Always make the change: it does wonders.
2) Do it if you have extra cash: it'll help but it's not necessary.
3) It's a preference thing: It has it's advantages & disadvantages.
4) It depends on the composition of the current nut or saddle.
5) Only do it if you are having issues.
6) Don't do it. It's expensive & doesn't give you anything.
7) Bone sucks.

or something else?