IF you don't care about sacrificing Qi wireless charging then a mag case would be really nice. I wonder if it would interfere with the antennas. The iphone has those ugly plastic bands in the aluminum for the antennas. It might significantly hurt reception
I'm not trying to rain on anyone's magnesium parade here, but I think it should be pointed out that darth is correct.
Yes, it will totally sacrifice Qi wireless charging.
Yes, it will interfere greatly with the antennae. The only way to prevent antennae interference is to ground the antennae itself to the metal casing, which is not possible as it is embedded with the plastic part of the phone.
There are several reasons that Microsoft goes with the Polycarbonate case for the phone. One is that it does not interfere with signals and allows the antennae to operate at peak efficiency. All metal cases interfere with and impede greatly the cell signal, Bluetooth signal, Wi-Fi signal, FM Radio signal, yep. Every type of radiation/signal produced is dampened by a metal case. This is why the iPhone has plastic strips in place of metal where the antennae is located. Check it.
Another reason that polycarbonate is used is due to its durability. Did you know that polycarbonate is used for bullet-proof glass? Did you know if you drop your phone, the polycarbonate absorbs and spreads out the impact to minimize damage to your phone and prevent breakage?
Polycarbonate is actually more expensive than aluminum. While aluminum can currently be purchased at 6.5 cents per cubic inch, polycarbonate is purchased at closer to 41 cents per cubic inch. The polycarbonate price arrived at here is from converting sheets of polycarbonate to what they would be for the same amount in a cubed inch instead of a 1/32" thin panel. Polycarbonate is 6 times more expensive to purchase in raw material than is the aluminum, and it is also more expensive to mold into the desired shape.
The issue with metal interfering with reception/transmission is also why the Mozo cases only have metal on the outer rim, and use leather for the backing. It's a nice premium trade-off for not being able to put metal across the back of the case.