I think the thing that most people are forgetting when they bring up these PC GPU comparisons as metric for how things will turn out between PS4 and Durango is platform differences.
All the charts posted of the 7850 vs 7770 is understandable but honestly not too valid in trying to get the point across. For this reason, these benchmarks are ran at the exact same settings. There is no doubt that there is a difference of power between the two that is made slightly worse due to developers not being able to target those two cards directly. With that stated the same type of situation wouldn't happen in a console environment regardless. I'm not talking "coding for the metal" or anything of that nature (actually I am a bit), rather I'm speaking more on tuning each engine to run well on the given platform while still maintaining some semblance of parity. An example would be say my company releases Shooter Dudes 2, and we're pushing some great effects on one platform. In order for us to have "visual parity" and keep the framerates as close as possible we might scale back in effects on one platform versus the other. We might be using FP32 on PS4 and drop it down to FP110 on Durango, then we might scale back some particle effects, they might be 1/2 resolution on PS4 and we might scale them down to 1/4 on Durango, there might be a removal of a couple of decals in a level, or even the dreaded slight resolution drop. It's a visual difference that vast majority of gamers won't notice, but it frees up processing power and keeps near parity.
I fully expect there to be some framerate difference later on in the development cycle, but I don't honestly expect a full 60fps vs 30fps or 1080p vs 720p that many are expecting and extrapolating from desktop GPU benchmarks. The differences might manifest themselves in GPGPU/Physics type scenarios more than anything else. My two cents on the entire thing.
/shrug