Morbid Saint isn't really "little known" these days, your about 5 or 6 years too late for to call them that. They blew up randomly in about 2004 or 2005, suddenly and without warning. They also have a second album, Destruction System, that was unreleased. It can be heard on the Keltic Records re-issue of Spectrum of Death (I'm not sure why MA calls it a demo, it was not a demo...).
Aura Noir was always slightly overrated, though they are pretty good I agree. Nocturnal Breed or Occult was where it was at as far as 90's black/thrash. Devastator is where it's at now...
Nargaroth is a joke. Awful stuff. On top of being entirely mediocre, did you know the guy behind the band claimed he started releasing album in the 80's but wasn't even old enough to have done so...the first Nargaroth tape showed up in 1997, he then lied about being in contact with the Black Circle and several other well known black metal groups to try to build scene cred. Sort of lame if you ask me.
If you like Proscriptor, check his first band Magus, killer doom/death/grind stuff. They have an discography called Ruminations of Debauchery that isn't too hard to find at all. It's his best stuff in my opinion.
Brann's drumming was best in Today is the Day. Mastodon has been terrible to me since right after Remission.
If you think MP is tough to please, you've never had to deal with me before...haha.