I'm rather skeptical of that as a fix. I reckon it's a hack that only works
if you aren't aiming for equal temperament tuning.
i.e. it works if you stick to the usual guitarist chords,
but otherwise makes the guitar untunable.
All guitar tunings/intonation methods are 'a bit of a hack' as long as you're using fixed, regularly spaced frets. The Earvana style nut just distributes the hack at each end of the string instead of just one end.
All it's doing is making all the fretted notes on the G
string a bit sharper
All the strings get a bit of compensation.
I know the Earvana nut is all wrong *in theory*. But in practice - on real guitars - it works just fine!
Just moving a standard nut a millimetre or so closer to the first fret achieves much the same effect. Many high-end (esp. acoustic) guitar makers use that trick.