Fredes, fantastic work. I watched your youtube video and left a message but here is probably better. I will build the same guitar. Buying a JTV69 this week, and then looking for a second hand Fretlight which might take some time, who would buy one? If you have any helpful tips then please let me know. I have built several guitars (standard items) so am not frightened to pull a guitar apart so would just view this as another project. I can't for the life of me wonder why Fretlight haven't done what you have done. It has a certain inbuilt market resistance anyway, (guitarist being a conservative lot), but a sound issue built into the design, is crazy. I have seen Fretlights answer to your criticism in other youtube videos, but it doesn't answer why build such a flawed design?
Hopefully you will find this enquiry in the fullness of time. Best wishes Bob.