I think I already mentioned in another thread a while ago that their debut album "Life Cycle" was technical thrash metal in the vein of Watchtower's "Control And Resistance". The two albums which followed - "Steps" and "A Sense Of Change" - have nothing to do with thrash metal, yet are highly recommendable.
As regards technical/progressive thrash metal, I'd recommend:
Mekong Delta
Coroner
Toxik
Watchtower
Also try:
Hades - "Resisting Success"
Voivod - "Dimension Hatröss"
In addition to the ones Burkhard mentioned above...
Anacrusis (Manic Impressions and Screams & Whispers)
Depressive Age (First Depression and Lying in Wait)
Realm (Endless War and Suiciety)
Skeptic Sense (Presence of Mind)
Thought Industry (Songs for Insects)