Wulfthar, I have a new F512 rosewood and a 1990 JF30-12. I am interested in hearing from you, and others, the tone differences you hear between your JF30-12 and the Oxnard F512 maple. I have never seen an Oxnard F512 maple first hand and have been curious to hear a comparison by someone who has experience with both.
At first : they were both Guild 12 strings Jumbos in maple, therefore the sound is similar.
Having said that the JF30-12 was an old school Guild : overbuilt with a big U neck that accomodated two truss rods, straight bracing etc...in order to make a guitar that was safe to use a concert pitch. The sound was very good but not as powerful in terms of volume that a Martin HD28V for instance....not as much resonance.
The new 412 is significantly lighter than a Westerly 12 strings Jumbo but not as light as a Tacoma 412 I played I think in 2012, however the guitar is significantly louder than my old JF30-12. Also, slightly more sustain I guess but I have played the guitar for few hours therefore I still need to make a more detailed assessment.
Besides the sound, the neck profile is more C than U and while relatively thick it´s much easier to play than the JF30-12, action out of the box was almost perfect, I am really impressed by their work, in particular how they cut the nut and saddle.
Finish was also better, but of course I am comparing a mid level model like the JF30-12 with the top end, a more fair comparison would be with a Westerly 412.
P.S. From the specs on the website I didn´t get if the top is Sitka or Red spruce as the Tacome guitars were made from.