ASUS ROG Poseidon cooler

I'm interested in ASUS' hibrid cooler and I was wondering how the AIR temps compare to the directcu ii cooler?
Has the vapor chamber been compromised to allow the additional water cooled functionality?

Which GPU? Gonna need a little more info to tell you temps.

For the GTX 780
I'm looking for a replacement to my GTX 770 which just died on me, and I'm hesitant to get a GTX 970 due to the 3.5GB VRAM issue

I just got a 970 for $150 and I haven't noticed any issue with it.