To Quote Bob Colosi... "Bone increases clarity and sustain, provides better overtones, and provides a better high to low end balance. It provides a much more “focused†high end and punchier low end, and is not at all shrill like some plastic saddles render the guitar. Additionally, bone will long outlast the factory installed plastic saddles."
That pretty much sums up my experiences as well... I have bone saddles in 5 of my acoustics, Tusq in one and am shaping an Ivory one now for the newest addition. It's the best upgrade in tone for the money that you can make (IMO).
As far as shaping them... You can order square blanks or ones that have been radiused to match your fretboard so you have only minimal fitting/adjusting to do. If you have a spare, you can remove the one you have in now and send it to get it matched and then just put it in... It really all depends on how much you want to invest.
You can find bones saddles at almost any music store. StewMac is a great online supplier that I use often http://www.stewmac.com/shop/Nuts,_saddles/Acoustic_bridge_saddles/White_Bone_Saddles.html?actn=100101&xst=3&xsr=42 Also Bob is a great guy to deal with http://www.guitarsaddles.com/products.asp Even ebay has loads of them...
[b][color=#FF0000]If your brain is part of the process, you're missing it. You should play like a drowning man, struggling to reach shore. If you can trap that feeling, then you have something.
[/color][/b] [b]Peace of mind. That's my piece of mind...[/b]