Only one problem i have with these so-called metal shredders, and that is they seem to hide behind their overdrive/distortion. Hammer-ons, pull offs, finger tapping, arpeggios etc... sound really good with the aid of a noise box. Tell them to play the same licks on an acoustic guitar, & they fall over every time.
With the exception of Malmsteen, who can shred on either.
I know, i used to be one of them. I went through a metal shredding phase when i was younger, & eventually got bored with its one dimensional simplicity.
Jazz, classical, gypsy jazz, flamenco etc... utilizing ALL of your fingers (instead of a pick) while at the same time incorporating very complex chords, bass lines, as well as shredding a few licks/arpeggios in between etc... thats the REALLY hard stuff.
Took me years to realize this.