Have I am on my 3rd season with a pair of Game Ear IIs and wish I woulda bought them years ago! I have killed my two big bucks in the last two years (one 14 pt 154inch gunkill and a 131inch 8pt bowkill) and each time I heard them coming before I saw them and was able to get up and get ready.
I originally bought them for hearing protection because I got a Sako/Lazzeroni Warbird that I had a KDF brake installed on. It is THUNDEROUSLY loud and I didnt want to have to keep hunting with muffs around my neck. But after only a trip or two with them, I use them for ALL kinds of hunting. I wear them bowhunting because of the ability to hear so well. I wear them turkey hunting because you can hear birds MUCH farther than can believe, and I also have learned that I can hear other birds with an " approaching tom" and that allows you to tell which ones already have hens with them long before you can see them. I wear them dovehunting not only to protect from repeated gunblast, but they allow me to turn them down yet still hear normal conversations and " calls" from hunters across the field letting me know birds are coming my way. For gunhunting they are superb. And using them for waterfowl hunting is simply " cheating" lol. Likewise I use them when target practicing. You can still talk to others without fighting muffs.
I bought two " pair" so that I have one unit for each ear instead of relying on only one. This helps with " stereo" hearing as well. It takes a lil practice to learn what is directly behind you vs direactly in front of you (before you can see them obviously) but you certainly are " on alert" long before the game is in view.
My brother and some other friends have since gotten the " custom hearing aids" from an ear doctor that are custom molded to the ear and are no more expensive than buying two pair of Game Ears. They are more comfortable than the Game Ears but I havent used them in the woods to know the performance comparisons, but I would certainly look into them if I were you or your buddy.
I am only 32 but wish I woulda " taken care" of my hearing better since I started shooting/hunting as a early teenager. A couple of years ago I started noticing my hearing wasnt the same (to many years of guns, rock music, Harleys and fast boats). At least the various " hunters hearing aids" bring back your hearing and prevent further damage.

My brother is a dealer for Game Ear and they have NEVER had a customer who bought them that didnt just rave and love the products,
RA