BLASPHEMY!

When compared with other bands of the time their stuff is relatively mild in its thrashy nature IMO.

Still thrash metal, but barely.

People saying Metallica's early records were not thrashy are no better than those saying Iron Maiden isn't metal because it's not heavy enough. Around MoP they started adding in more Heavy Metal influences, but even then.

Kill 'em All, despite being very good, had a lot of speed metal tendencies in it, and RTL and all their other albums were pretty melodic.

Since when are thrash and melody mutually exclusive? The genre does not begin and end with Kreator and Dark Angel, people. Slayer's debut is rife with NWOBHM influence, but it's still thrash.

they did, well Blasphemy didn't ;p
but Napalm Death did

Well, I'm surprised nobody mentioned Satyricon. I love the Shadowthrone and Dark Medieval Times but it went to hell from there.

Listen to Scum, From Enslavement to Oblitarteration and than compare it to Harmony Corruption. Than, compare Harmony Corruption to later 90's albums. Finally, take something like Words from the exit wound and compare it to Smear Campaign. They have changed alot and often through out a period of every 5 years or so.

The obvious mentions would go to Cathedral and Trouble, both within the doom genre.

Cathedral's first album was totally different from everything that was released after that. That album was a dark, brooding masterpiece of heavy, and in a way really trippy, doom metal. The later albums ditched the dark and unpleasant vibe, while still being very trippy doom metal, although in a more "heavy with a focus on being heavy" kind of way rather than the "heavy with a focus on darkness" kind of way that was used on the first album. IMO all Cathedral albums are varying degrees of awesome though.

Trouble's early material was very traditional in it's interpretation of doom metal. After their debut though, they steadily progressed to a more drug-influenced sound, while in the end becoming full-fledged stoner doom. It's also very interesting to listen to their albums in a chronoligal order, since I believe it can be used to get a glimpse of the personal and emotional develpment of the band members. You can hear the sorrowful, god-praying tunes of their early work slowly transform into a more "I just don't care anymore" approach on their later albums. It's one of the few bands where you can actually hear something like this, almost like a narration, simply by listening to the music. Trouble is one of my favourite doom bands though, and I love all of their work.

Another band that's changed a lot between their albums, but still staying within the same genre is Electric Wizard. All of their albums have a very distinctive sound, but they still manage to accomplish the same things and bring you the same type of enjoyment. They just use different approach to achieve these qualities with each one.

I think they kind of changed from traditional doom to a kind of sludgy doom, and then to stoner doom...
But your pretty much right.