I have a Johnny A Standard w/bigsby...Challenges to keep in tune, but not too bad normally. Anyway I took it in too a very reputable guitar tech and he made a couple of observations that I wanted to run by you guys. He said the nut they used was junk. Even with some work and "nut sauce" probably going to have a problem since I'm running the bigsby. Suggested a bone nut or a Tusq XL which will allow strings to slide much better. Also noted that they used an older style ABR-1 bridge which has the narrow saddles, which in turn does not allow the strings to move as well and thus more of a challenge with a Bigsby. Kind of surprised considering the dough I spent on the Johnny...even the standard. Thought I'd get some input. Maybe on the higher end signature they used a newer bridge design and better nut material?