I want to use framebuffer_multisample and framebuffer_blit for AA with deferred shading. The idea is to render all the g-buffer contents (normals, eye-space positions, material indices etc.) into FBO render buffers, and downsample them & copy them with framebuffer_blit to textures for further processing.
However, I noticed one thing: if I use multisampled FBOs, I essentially multisample the g-buffer, and not the end result, while regular AA in forward renderers does. Edge detection/blur algorithms for deferred shading also operate on the result. But is the difference visible? Does it matter in practice for the image quality that the multisampling happens on the g-buffer?