From my testing, EA and MA Abysia are immune to any income effects from death/growth scales at all. They get penalized with death-3 income no matter what death/growth scales you take.
Try it out: create a game with MA Arco and MA Aby. Arco has neutral scales and Grow-3, Aby has neutral and Heat-3 + Grow-3. MA Arco will have about 415 income. MA Aby will have about 345. (This is CB, so 3% per tick).
Now try a game with MA Aby and Heat-3 + Death-3. Again, you get 345.
So, sucks to be Aby.
With grow-3 you're paying 240 design points for no extra income other than that eventually generated by the extra pop you get. Of course, the growth does help your mages, and also keeps some people around you you can maintain blood slave income without invading your neighbors like a crazy man.
Personally though, I'd prefer to be the crazy man.