After about a year and 1/2 of ownership, I took the Air Jacket off to have my iPhone serviced and I did notice beforehand there were some light scuff marks on the shiny chamfers. They really can only be noticed up close when angled under a light source. Those chamfers are really easily scuffed though. There weren't any other marks or scratches anywhere else on the phone however. It's pretty subtle, so much so that I think I can still advertise my iPhone 5 on craigslist as excellent or near-mint condition.
I don't think it'll be an issue with the 6 since it doesn't have any fragile regions like the 5 did.
I saw that in your other thread. How are you liking it? Does it add any noticeable thickness to the phone?
I ordered a pack of Spigen Crystal plastic films as a temporary solution and to see whether I can tolerate the cut-outs. 10 bucks so not a huge deal. The Feather+ would probably be my first choice if I ever decided on a more permanent solution.
The Feather+ is awesome. Unlike the Ghost, there is no noticeable thickness added and feels much thinner when your finger is looking for the home button. The only issue I can see is since the curved areas are not covered, the edges of the glass may attract dust/lint if carried in a pocket (as I'm sure most guys will). Nothing a quick wipedown won't take care of. Despite a few shortcomings that other manufacturers have also encountered, I am very satisfied with the purchase. Quality you'd expect from MIME.
One thing though- I seem to remember in years past the lifetime discount for a broken protector was 50% right? On the site now it seems to be 40%. Not an issue for me, just curious.