For someone who has been making saddles for over 15 years, I really cannot recall the last time I made one with micarta. Maybe the last time I used one was on a 1996 Martin D-35 acoustic guitar. Since then, I've never really taken the notion to try a saddle of micarta, at least not until now.
Micarta was used in Martin guitars for quite a while. It wasn't until the "vintage" craze of the late 90's and up until now that people wanted genuine articles in their Martin reissues. That meant real bone and fossilized walrus ivory as saddles. Martin used elephant ivory for many years in the pre-war models. So Walrus ivory seems like a good approach today for the reissues to give people that "vintage" feel. Problem is, walrus ivory is just a bad bad idea for most guitar saddles. Maybe it can brighten up some old bass heavy Martins, but for most guitars, people always go back to bone, solid, neutral tone.
TUSQ, a new invention of recent, works better for most ivory applications. But still, TUSQ I think is a bad idea, unless used on guitars where an UST is used. Its uniformity works great when your plugged in. Unplugged, not good, at least for most instruments... again unless you desire that ultra-tinny, bright sort of tone.
Now it brings me to micarta. A plastic saddle. Where this material excels as a saddle is when you desire a more focused, or "compressed" tone, a more fundamental tone, with less transients and less overtones. Sounds like something bad? Not so. Sometimes more transients and too many overtones can make the guitar sound hollow and "woofy" sounding, where the fundamental note is lost.
I used the word "compressed" to describe the micarta sound because I think it attempts to do what a compressor does in audio reproduction. Since I have a background in recording, I am intimately familiar with the use of a compressor.
A compressor simply reduces the amplitude of those louder transients, and lifts the volume of those softer ones. If you think of a compressor as "squeezing" the sound into a nicely focused wavelength, then you have the right idea. The result of sounds going through a compressor are generally more pleasing to the listener. That's why 99% of the music, voice, talk radio, anything you listen to ultimately has been compressed in one shape or another.
So, if you have a guitar you are not truly pleased with because its either, "woofy", or too uncontrolled sounding, and you desire a more focused sound, then I think it may be worth a try to strap on a micarta saddle. Some folks have also descrbed its sound as "woody", which basically means, more of the fundamental tone of the instrument. The instrument is made of wood, thus, its fundamental sound is wood. I think micarta does that well.
I really haven't noticed any less sensitivity either. Less finger noise, yes, less fret noise yes, less scratchiness, yes. I can see this saddle being an advantage on a spruce topped guitar.
The one disadvantage of micarta is that it is soft. Very soft. What happens over time, is that the wound strings will begin to dig little notches in the top of the saddle. With that comes buzzing, and string breakage unless you address the issue. Perhaps that is micarta's true failure for some, especially those who use higher tensions.
Why the long post about micarta? Well, simply, because its not a material you see much information about here on the delcamp forums. Maybe because delcampers are generally traditionalists, and use of any strange man-made materials are taboo..