Yeah I'm thinking the lower growls are Anders' backing vocals which is why they sound sweet. After listening to it a bunch of times I can say that while I don't feel the vocals are on par with Bloodbath which has always had amazing vocalists, the vocals don't really hurt the music overall. They are not mixed to be out front so they are not that distracting, and they do have a bit of a unique sound on a Bloodbath track.
If the guitarwork is all like this I think I'll still enjoy the album a lot. Actually I like how this album sounds in general, it's a bit of a throwback to RTC days but it doesn't quite take it that far. It has a modern edge.
Still, I can't even imagine how great this could have sounded with Peter, I think his voice would have fit right into this track.