I have backed this project on Indigogo and got my pledge recently.
“https://www.indiegogo.com/projects/muconnect-faster-safer-and-magnetic-charging-apple-android/x/12842391#/” It is a swedish company. The µconnect pro version I am relying on
Generally it works and also it is quite slim in format. It should fit just as good for FP1 as it does for FP2 leaving enough space for the headphone jack.
It snaps on easily and works in both directions.
Although both parts are magnetic, I think the magnets are a bit to weak which makes it necessary not to move the phone when attached or the cable will loosen/fall off interrupting charging or more severe interrupting data transfer.
Synching works fine if the slide-switch is positioned correctly.
There is a difference in charge current/speed between the two switch positions.
One for synching the other for fast charge.
But nevertheless if in fast charge position you still loose a bit of current through the adapter itself compared to connecting directly without µconnect.
Maybe the pins can´t handle more current or the cause is the internal design.
From about 1350mAH charging current without adapter I´m loosing about 300mAH with it leaving some about 1050mAH to charge. Actually it is only a small adapter being attached no entire cable.
I think if it comes to size there is not much choice. But I do believe some others are having stronger magnets and a more reliable hold.
Considering current it would be interesting to have a comparison with other types.
µconnect was about 16$ for backers and is now after about 20$.
I guess in this prize range there is even more selection.
Around christmas I also ordered the cable of “GOOBAY” at the electronics dealer Reichelt. Order No. is GOOBAY 40912 - 8,95€.
I think it is even better than the one I had first and it does not have any switch for synching and fast charging, it just does both without loss of current through the circuitry. It is about 1,2 meters long and the connector is directly attached to the usb cable. The cable is coated with textile and very flexible. The hold of the magnet is slightly better than with µconnect as the plug is a bit shorter, as it is no generic µusb-B adaptor but directly fixed to the cable.
Both designs are quite similar, so I wonder who had the idea first and who done a “benchmark” and build his own version. Even the magnetic plugs match and can be exchanged. There is no difference in operation. I now prefer the Goobay version as you don´t need switching and the hold is slightly better. One drawback there seems to be. But I guess this relies to all magnetic connectors.
The maximum current the contacting pins can take. Goobay states 
Assumable most devices draw more than 1A continuously (FP2 ~1,4A). So it may be a matter of time until the pins are spent and the entire cable turns useless.