Sam - Counterpoint emphasizes separate melodic lines moving against (counter) eachother, rather than the use of chordal harmony. Classic examples would include early choral music and much of the of music of Bach. Canons and Fugues are contrapuntal. GH examples would include the beginning of "Tales of the Great Wars."
Theremin - Echolyn uses 12-tone composition very sparingly - but here's an excerpt from Echolyn's website (
www.echolyn.com) that explains their use of it in an instrumental interlude "Only Twelve" (from album Suffocating the Bloom):
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CHRIS: There's only twelve notes in our Western music system. I decided to take some of my knowledge and apply it here with the band. Starts with one 12 tone row (violin) accompanied by a different 12 tone row in the cello (played rhythmically expanded from the first), and then joined by a third 12 tone row (viola) that rhythmically follows the first. (If you don't believe me or don't understand, I'll be glad to explain it in layman's terms.) Finally all three rows are joined by chords that harmonically place the tones in an analyzable chord progression - leading us back to the traditional tonal system most of us are accustomed to.
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The nice thing about Echolyn is whatever theoretical approach they use, it always sounds good. You don't have to have a degree in music theory to "like" the music, although the more theory you know the more you will appreciate what they're accomplishing.
I guess I should add that Echolyn is my all-time favorite band (although if GH puts out a few more albums like Lex Rex, that might change

. You absolutely have to hear Suffocating the Bloom and As the World - start with those, but all their albums are wonderful (IMO you probably should not start off with Mei). Make sure to give them a few listens before passing final judgement. Not quite as accessible as GH, but very rewarding.
They're also Christians and have very inspiring, though not overtly religious, lyrics (for example, check out the song "Never the Same" from As the World) if that makes a difference.