Well, Terminal Spirit Disease sounds much closer to SotS, than the first two full-lenghts. TRitSiO is much more rawer, more technical and less produced than SotS. There are some similarities, but not many. Also, this album has a violin player and I think it fits here 100%, although he appears only in few spots.
In my opinion, all ATG material is awesome, but it keeps evolving through the albums and without Tomas you might not even think you're listening the same band when listening The Red and then SotS.