I've never understood the love for focus peaking.
I've just started playing with it. I found it somewhat useful when I was using a 600mm manual lens on a monopod. Very difficult to maintain a steady viewfinder when magnfied. So backed off magnification to half and used peaking.
I believe I use this but at 14x and a 600mm lens it is still too bouncy to achieve focus. Maybe just my poor technique...lol. So I use the wheel to back off to about 7x magnification and use peaking with nice resultsHidden in one of the settings menus (Custom menu (Cogs) -> C. Release -> second from the bottom on the first page) is an option called "Half way Rls With IS" which has the description of "When set to On, Image Stabiliser will work while the shutter button is being pressed." The current description dates back to before the camera was released, I can't remember exactly when it was changed however it should read something closer to "When set to On, Image stabiliser will work while using zoomed preview or the shutter button is being pressed.". Basically when you zoom in using magnify, IS kicks in and you get a nice steady image to work with, it's really something magical. My one caution however is if your camera gets turned on inside your bag by the time you notice the battery in the camera (and grip if you use one) will be dead. It also has uses when doing hand held HDR as it prevents shutter shock by turning the IS on before the first frame is taken rather than as it's taken - I often find that if I have it turned disabled I get shutter shock on the first frame of HDR's taken on a monopod, it's sort of a workaround in part for not having EFCS on high speed mode.
I believe I use this but at 14x and a 600mm lens it is still too bouncy to achieve focus. Maybe just my poor technique...lol. So I use the wheel to back off to about 7x magnification and use peaking with nice results