I am the USA distributor for the USA version of the Nest NT-530H carbon fiber gimbal head.
The USA version of this head has been factory modified and warranted to be ARCA compatible for all ARCA standard plates. The Nest mount contains a special stainless steel security pin that prevents the QR plate from coming out of the mount without releasing the security pin, no accidental dropping of your gear that way. The mount is unique in that the QR plate slides in from the end rather than drop in from the top, this allows for quicker setup as your tension clamp only needs to be turned 1/2 revolution from lock to free and back. This compares with 4 to 5 full revolutions for most ARCA clamps. The Wimberley, RRS, Kirk, Desmond and Kiwi plates will all fit the Nest, but because they use the two security lock screws to prevent accidental slide out of the plate, the front screw will have to be removed for insertion into the Nest mount, the rear screw can stay in place for security purposes.
The Nest NT-530H comes supplied with one 6" long QR High Security plate and extras are readily available. This head sells for only $299 complete, plus shipping, and is ready to use right out of the nice padded carrying case that is included with it.
The head may be found here directly: wwwcameracottage.com/equipment