I'm glad I saw this, because I was actually going to comment on the production of this album being above TIAH. Granted, I haven't given TIAH a listen in some time, but the production on that album never sat well with me. I thought Sempiternal sounded better, but I may have to go back and listen to Hell now.
It may be a subjective view, but TIAH sounded much more vast to me and you could easily pick apart the guitar sounds and such. I love Sempiternal (after a few listens) but the metal aspect of the band is very hindered thanks to production.