The guitar, BTW, is the JF4 I just picked up for a song on Craigslist. I replaced the plastic saddle with bone. I have to say, this is a surprisingly great-sounding guitar.
I played it hard for about a week with the plastic saddle it came with so I could get a better sense of the improvement (if any) with bone. A tad louder perhaps, but the most notable change was greater clarity between strings, especially on the 5th and 2nd strings.
Though I have a couple maple archback jumbos, I was unfamiliar with this model. I never would have gone after it, but jeez Louise it was so cheap!
Very glad it came my way. It's as good in its way as my F50.