Hi Nitro, I'm in the midst of setting up a 4x2x2 as well. From what I understand, the flowrate should ideally be 10x of the overall volume therefore your 2xAB2000 might not be enough....I think. I'm planning for 1xAB7000 but still in two minds if I should do 2xEheim1262 instead or not since I have AB needlewheel pump failed on me before. The next concern for me is the power consumption, AB consume less energy but Eheim is definitely reliable. Its a neverending headache!
Wish you all the best in your setup