Re: Mike Pourtnoy
I really don't like the attitude of Portnoy, too much show off and that can be felt in his playing. Anyway there are lots of interesting things to learn by listening to him. But I really prefer in that style of music (DT or Liquid Drum Theater) drummers such as Sean Reinert (Gordian Knot, Aghora, Cynic) or the work of Marcel Dissantos in Atheist.
As for Necrophagist, on the 1st album it's a drum machine and on the second album it's "just" excellent Death Metal drumming (and I think that Muhammed Suicmez playing the guitare is what makes the difference in this band, not the drumming), anyway you can find such stuff in Iniquity, Psychophagist, Lost Soul and the list is almost endless.