Heh, Atheist is probably the best example of a tech-death band. Death, well, they're ok I suppose. Also, lol Tool as prog metal example. Not that they're horrible or anything, but there's less generic bands that are more prog that you could use, e.g. Ayreon, Strapping Young Lad (HELL YEAH YOU [bleep]ING SUCK) or Pain of Salvation. And prog isn't necessarily guitar-led, lots of prog bands alternate between drums, keyboard and guitar often. Dream Theater is guitar/keyboard alternating, whereas Ayreon has the emphasis on the vocalists, and Opeth has the emphasis on twin guitar attacks and jazz-influenced playing.