Actually, the Sony AVC and other render options are missing when I choose "render as". I can modify and save variations of the existing render options that do show up.
Many people, including me, had this problem on some platforms because of video drivers. See my response in this post. I haven't seen the bug since then, but I didn't change video drivers for a long time after I was burned.
There are also check boxes for which render options are presented in the Render As dialog box.