Just a piece of information to add to the printer-scape for an FT-5.
Please don't shoot the messenger.
FWIW...... 
OK, I just had to try one.
Prior to this I really didn't have much, if any, of a leveling issue to start with.
That is because I run doubled corner bearings, linked Z motors, three point bed leveling adjusters, and a very rigid and stable Z stop.
As a result I basically only had to re-level the bed and adjust the Z stop more or less when I changed nozzles.
But I like to experiment with things just to see what all the fuss is about.
So I purchased the GeeeTech version (yes, I know....
) fully figuring that I would purchase a real BL-Touch later if I liked the results and felt that there was promise to it.
First of all, with the controller I am running it was somewhat of a PITA to set up requiring the use of an oscilloscope to diagnose it.
Theoretically it is a simple thing but I had to experiment with several versions of Smoothieware before finding a version that would accept the PWM commands and execute them correctly.
However, finally I did get it to work.
I must admit that it was quite interesting to be able to dial in the first layer thickness merely by setting an offset, and especially so from the slicer (Cura).
But I could do that anyway with the regular sensor.
So far so good.
However-
The sensor rattled like mad from the start when the motions were running (even in 1/32 step mode) with prominent resonance points in the motions.
And it was clearly self-destructing, to the point that the probe is visibly no longer parallel to the sensor body.
Finally, this past weekend I fired up my printer and could not get a decent first layer to print, spending hours trying to tune and fix the problems.
So eventually I commented out the commands to deploy and use the sensor and went back to using just the regular Z stop sensor, and guess what?
The problems then completely went away and I was able to print things again.
Now I know that GeeeTech is a cheapened version of the AntClabs sensor who protest that its competitors are giving it a bad name.
I get that.
Though coming from a company in a region infamous for IP piracy that sounds a bit hollow.
But seriously, I feel that there are two fundamental flaws with this type of sensor, regardless of its source.
First, there is little or nothing to keep the probe tip from moving side to side.
Hence the rattling and wear.
Second, and much more important, the use of a hall-effect sensor and a magnetic armature to precisely sense vertical (axial) position is suspect to begin with.
There are too many things to go wrong with both items.
So, I am not impressed and frankly I really didn't need it to begin with.
Your experiences with these (including AntClabs versions) may be apple pie and sunshine wonderful.
But if the machine is set up rigidly to start with, I really don't see the need.
So into the scrap box it goes.