I use the R7 on one body. Bought it as a result of a similar thread to this about 12 months ago.
I then bought a Chinese knock off called a quick rapid, which I'm just as happy with, for about 1/3rd the price.
There are a few on fleabay but not all have the same connection to the base plate as this one.
http://www.ebay.com.au/itm/Quick-Rap...item3cb89b803d