Damn don't mention job hunting, I keep postponing my shit.
I'm actually not a huge Therion fan, i've heard several of their albums including the ones you mentioned. I think they may be one of the first symphonic metal bands. Mostly all have certain redeeming qualities, but Theli and Secret of the Runes are my choice picks.
It seems Therion was progressing and developing until they hit Theli where they lost a lot of their death metal sound.
I actually heard Bal-Sagoths "Battle Magic" maybe a year or more ago, I remember it had a lot of keyboard sounding shit and funny sounding vocals. I don't remember much just that it sounded dense, and I ended up deleting it.
Downloaded Sigh's Hangman's Hymn.
Would you say Imaginary Soniscape is your favorite album by them?
They remind me of a crazier version of Arcturus, I'm assuming you've heard of them.