As said above, the BCF will work fine with FCP & STP.
The problems associated with overwriting automation data is that whilst the BCF uses motorised faders to playback the automation, they are not touch sensitive. This means that you have to physically fight the motor to get them to drop into write mode when they are playing back data, and will not automatically drop out of write when you release the fader.
You can work around this by manually dropping in and out of write modes, but it does become frustrating.
I've just come back from a trade show and I've been playing with the new euphonix controller.
http://www.euphonix.com/artist/products/mc_control/
It's cheaper than the Mackie, and feels great to work with. It's faders are touch sensitive, as are all of the control knobs, and drops in and out of write automatically. As it supports the Mackie Control mode it works with FCP / STP without any problems, altho I haven't personally tested this yet.
They also make a fader only version which is cheaper, and to be honest and less you need the transport controls and the touch screen this would be fine for mixing in FCP / STP.