The major difference I found was having the nut cut down so the strings are only half + a little bit inside. This may require a few ons and offs of the strings, but likely will diminish tuning issues by far. In case you only bend up or only bend down (by pushing the Bigsby), just do it during tuning and you'll be fine ... it's only tricky when you want both - but having both, to me, makes the guitar fully usable, so I don't really see a point in not setting it up complete and right. And it's quite rewarding, as you do it once and then play until the nut is worn, which will likely take months or even years. Old lubricant has to be removed and replaced, as it only works as long as it is a fluid, but any grease will turn solid after a while and therefore should be taken off. The string butler ... hm, I thought about one, too, but it is really ugly and, while reducing friction in the nut, it still adds another spot of potential problems, so ... no. In general - there is no frictionless vibrato unit of any kind. There always will be a bit of detuning in at least one direction, but if you get through the longest song with the most bends and vibratos without being out enough to have to retune, it can be called perfect, or as close to perfect that any more is more of academic interest than practical advantage.