[Tolkien]

It really depends on your scales. If you, for thematic reasons, massively take death, then Demonbred would be your go-to option. If you have some growth, then the Apprentices become viable, as with good growth, you generally won't lose too many to disease.

Finally, SDRs are definitely worth it. Along with the +10% chance on your blood 2 hunters, you also get +1 blood slaves per turn guaranteed. Forging with a hammer, it pays for itself in 7 turns (just with the +1 blood slave and with a Dwarven Hammer).

As for labs: you can if you have the gold (because they do cut down on micromanagement, alot). Personally, I use indy commanders and scouts to ferry blood slaves around for me if I'm tight on gold. 30g/20g and 2-1 upkeep means that they're economically more cost-efficient then labs; unless of course the game drags on for 235 turns, of course.