My experience with Evertune;
It's fun to just play and go nuts without having to worry about tuning for a couple of months before a string breaks, absolutely.
But it intonates "too good" and I had to autotune bass when recording with the Evertune guitar I had.
This might be individual, but the sustain sucked completely on the higher notes. It was okay for rhythm recordings but I couldn't use it for certain solos with long notes.
It sounded a bit thin tho, even compared to my Floyd Rose guitars.
The intonation "issue" was apparent because I couldn't have other guitars on top of the Evertune tracks, because they intonated differently.
I couldn't play along to CDs or anything either. I have never had that problem with my other guitars, be it hardtail or Floyds, and I'm picky as hell about intonation.
I tried record every single note on a couple of my regular guitars to a synth, and I could hear slight intonation differencies... Not so much with the Evertune, it sounded a little better on every note.
So, yeah, it sounds better on it's own, and with an autotuned bass it can sound fantastic!
I recorded this whole album with that Warmoth except solos and whammy things:
So yeah, it's definitely useable. But I sold it not long ago because I got tired of the intonation and susatin and shit... And now I regret because I know they can be used for certain things...
But because of sustain/tone I prefer "hardtailed" double blocked Floyds, or Big Bends Nut Sauce now