I've got about 450hrs on a recently installed Furutech GTX NCF and sharpness in the highs is no where near it's description, it may sound that way somewhere through the brun in process but no different than any other outlet sounding shrill harsh etc.., it will sound as neutral as your system is. The overall sound is wonderful and like no outlet I've tried combing attack , slam and lighting fast transients with bloom , sound stage integrity and harmonic structure. I stayed away from this outlet for the very reason you described and after a late 2021 system upgrade it was the more than a cherry on top but another layer to the cake.
I like to use, what I deem as system synergy, to get the sound that engages me. Anything else like outlets, power cords etc, should just let that synergy shine more, not change the character through synergy.
I've tried many outlets and at the time, each one seemed to sound better. I just have to remember that my system has changed several times as well.
I would suggest that the Wireworld Stratus 5 cord is replaced with something else. I have the Wireworld Elektra 7 and it doesn’t sound too good when used on amplifiers. It sounds decent on digital but not on amps.
The Furutech GTX-D NCF outlet is very good. The only downside is the long burn-in period before it starts to sound stellar. Approximately 500 hours before you hear a sudden change in the presentation.
@divertiti Sorry for the late response ! I also currently have in the same 4gang box the AQ Edison outlet which replaced an PS Audio premier . The AQ Edison is no slouch by any means and could easily live with it I give an edge to the NCF due to dynamics and a bit more transparency without any sacrifice to musicality.