Yes it is a PS3 limitation, having the ability to change the FOV in a slider on the pc client is a huge advantage however I actually have this advantage anyways, 21:9 screens, considering the hardware market that pc gamers have anyways dunno why they just dont provide the settings anyways, we can already get around it.
People with 3 monitors already have this gigantic advantage anyways but I would also like to have the camera to pan out more since I actually like to keep an eye on people from further away.

Also yes, a greater FOV does mean more objects in render on your screen from a gpu horsepower point.

At 2560x1080 21:9 on a nvidia 780 gpu, I dont break 100 fps but on a standard 16:9 1080 p that wont be a problem and my settings are pretty much maxed, though in instanced content I never drop below 60 FPS and that includes ST.