I received the BLTouch sensor and must say it's very compact and should fit nicely in the left extruder space, apart from this if you connect a +5VDC to the sensor it will auto do a self test - led light on, pin will go down and up and then remain up with the led light on, with only a +5VDC connected you can lower the pin with your finger and the led light will go off, push the pin up will active the led light.
I have bad news, this sensor is controlled like a servo and therefore needs to be connected to a servo connection point on the FFCP board, Flashforge are unable to tell me which connection point(s) is/are servo if any is available on the FFCP board, ANTCLABS who is the manufacturer of the BLTouch sensor also don't know because they don't have a FFCP board. I guess I shouldn't be surprise because FFCP looks like a copy of the Makerbot Replicator because when you look at the Makerbot schematic it fits the FFCP.
Not only do we need a servo connection point on the FFCP board, we also need to know the G-Code to access the servo point. The G-Codes depends on the firmware, now this is where it can get very confusing, one would think it would be relatively easy to get a list of G-Codes for the firmware you are using, if anyone have a list of G-Codes for ReplicatorG(Sailfish) firmware please post here, if you search the internet be warn the G-Codes can be convoluted. I've tried with no success using M280, M340, M300, M301. ReplicatorG does not recognize M280/M340, and reports an error about pen plotter when using M300 and M301.

The only possible servo connection on the FFCP board as per the Makerbot Replicator schematic, is the PB7 point which according to the ATmega 2560 processor documentation is a PWM (Pulse Width Modulation) point - PWM is required to drive a servo. Further supprise there are two points on the FFCP board marked PB7 (I've tested it and they are not connected).

The light at the end of the tunnel is very dim.