Doom Drake's abilities just Pestilence + Death and Hell Drake's are War + Famine. There's a flat stat difference between the two Kami sets (20% additional stats with the exception of each Drake's special stat increase) but does it really make up for all the additional skills Drakes possess?

Edit for accuracy: The Drakes aren't a straight combination of any two Apocalypse Kami, but rather each seems to possess abilities from multiple Kami. In addition, each Drake has a gene combo ability, an Apocalypse Kami has none.