Cost efficient blood hunting

[WraithLord]

So currently its common knowledge that:
A. Blood hunting is most cost efficient on ~5k provinces
B. SDR on your blood hunters is well worth it (makes non blood hunters count as having blood 1 or some such)
C. Most cost efficient blood hunter are:
1. ???
2. ???

now, a list of cost (cheap) efficient (with or w/o a blood pick) commanders would be nice but I'd settle for deciding which of the following is better: your common indie scout or warlock apprentice.
Some points to consider. scout has 2g upkeep vs WA 8.66g; scout has 0 B, WA has 2 B;
Also, does SDR make any difference in that respect?

Cost efficient is naturally defined as G/BS ratio, i.e. how much gold goes for hunters upkeep (I discard provinces income from this calculation since I'm not interested in optimizing province size as well) divided by avg. blood slaves income.

I would appreciate any input on the subject.

TIA