End of suspense for MGO, i played and checked the demo
it's 1024x768 (100% sure) with temporal AAx2 like DMC4
my forecast was good
i think they use "max 1024" resolution like VF5 (VF5 is 1024x1024 and 1024x768) for improve post-process (and software upscale), in this case the framebuffer is like a texture and RSX is probably more efficacious for texture 1024x1024 or under (cache optimization or other thing)
1024x768 is also "64x64 tile compliant" and "4/3 SD format compliant", bonus advantage