The GPU can render to both pools but can it do it simultaneously? I don't know how (modern as GCN) GPU behave while handling say multiple renders targets.Well, several people here can't do simple arithmetic. 104+68 is 98% of 176. 98% is "the same".
For those searching data on the matter, hardware.fr has interesting charts (as usual ):ROPs requires bandwidth.
The 7970 has the same number of ROPs as the 7870 (from which the Orbis GPU seems derived), but it has 72% more bandwidth (higher clocked memory and a 384 vs 256 bit bus) and it's 3dMark Vantage pixel fillrate is 66% higher (13.3 GPixel/s vs 8GPixel/s).
This means the ROPs in 7870 runs at 60% utilization compared with a 7970.
Now Orbis has 22.4 GB/s more bandwidth than a 7870, but it also shares its memory bus with a 8 core CPU.
Cheers
http://www.hardware.fr/articles/856-7/performances-theoriques-pixels.html
It shows that the performance indeed tanks, either when using FP16 or with blending.
Still the figures is not as even as you seem to imply, may while blending the GPU could behave the same but there are other situation where the advantage should remain pretty sound (as far as ROPs are concerned).
Devs may pass on FP 16 (on both system if perfs are too low) and rely either on fp10 or a logluv /nAo32 approach.
In which case the PS4 ROPs will perform closer to their peak performances and at a significant advantage.