Yep, fully aware of that, but it's beside the point: I'm letting people know that despite suggestions to the contrary, both the 7D and the 70D will work in circumstances which some on here have stated they won't work in.
If you use a non reporting TC, even a old 10D will autofocus at f/8 with some lenses. Others do not work. I've tried in numerous bodies and lens combinations over the years. The TC you use also makes a huge difference, some work better than others.
They do not track a subject fast enough for bif, but for a still object in bright light, they work fine. My 5D MK III worked much the same way before the firmware update. It is now more stable with F/8 AF then it was with taped contacts or non reporting TC. With some lenses, it just rapidly vibrated the focus at F/8.