limeypride thanks for the hook up on the Syncwire magnetic mount. I didn't install it until this morning as luck would have it the plastic frame around my Spigen Neo Hybrid case broke and I was waiting for a replacement case to be delivered that finally showed up this morning.
Given that the case adds some weight to the phone (but not ridiculous like some of the Otterbox solutions) I opted for the rectangular shaped magnet figuring it will be more stable. Plus, to your point on positioning it gives a greater surface area so I can move the phone up/down against the mount. With the structure of the case I did not even stick the rectangular magnet to it as there is no way its going to move. With the rectangular magnet placed in the center of the case during a test drive this afternoon I was able to move the phone up to make access to the passenger side AC vent fully available. Win-Win.