I was going to say that too. Dave uses a lot of pentatonic licks ala Page but with a metal/crazy feel, especially on Kill 'Em All, assuming Kirk was copying Dave's original solos. I think that's fairly accurate but I'm not 100%. Some of the early boots of Metallica with Mustaine seem to support that.
I'm a fan of the Big 4? 3? Not so much Anthrax. So sad Jeff and Nick are gone. I think Jeff was the genius in Slayer and that says a lot in the world of metal, same with Dave. Dave does it all though, writing, vocals, lead, rhythm.
I'm not as big a fan as you but I agree. I never understood why they never made it bigger, had no idea of their management situation, it's soooo important.
I like them but I find their live show a bit boring, the drummer does too many songs which aren't very good but they do have quite a few songs that blow me away.