pat4027I know, that's what they said but I highly doubt it makes a significant enough difference to sacrifice the lack of protection on the top/bottom cutouts, not to mention how bizarre it looks... Getting dust and scratches in the shape of those angles would make me so mad. I've had around 20 different cases for my 6S+ made from all kinds of materials from aluminum to wood to leather and carbon fiber, none of them have had any noticeable impact on reception.
GudedomoCF will essentially produce a Faraday Cage, effectively blocking all signal. You obviously don't know (No insult intended) but we do a lot with carbon fiber and RC planes/quads, the antenna has to be open or the CF has to be very open otherwise it cuts all signal.
But yeah, it looks bad, and a carbon fiber case is pretty pointless anyways.