SO the xG3v1 is the better option of the 2 xG3’s for sensing.
If you really want sensing, I would recommend you seriously consider the Titan ( I understand the price and installation procedure may not be acceptable for you)
For announcements of when the next batch is being launched, keep an eye on this thread
To answer your questions I would suggest you check out this thread, even though the Titan implant discussed, it is a sensing magnet and the better sensing areas are mentioned throughout the thread
and this one
Hopefully, you will get some further suggestions from some actual Magnetos…( I don’t have any so I cant give you anything but anecdotal advice )