I have a theory about the F- prefix copies.
NOW BEAR IN MIND this is only a theory!!!
I think the F- prefix copies are from early on in the El Degas timeline, before moving to the standardized prefixes I've identified elsewhere. You also tend to notice some attempt at a serial numbering system with some of the F- prefix copies, which also makes me think that these might be from early on.
Now, if this theory is correct (and I'm not totally confident that it is, myself), would this make this guitar any better/worse/more valuable/less valuable than other El Degas guitars? I doubt it.
