I definitely agree with all of that. The atmosphere on that album is so powerful. Besides the four you pointed to, I'd also mention I Feel the Dark as a good song with a ton of atmosphere.
Pale Communion and Sorceress don't do much for me. They're both alright, but not particularly inspiring. I like In Cauda Venenum a lot better than them, but I wouldn't put it on the same level as Heritage.