Well, I thought this thread might be a good place for me to start out here.
I have a lot of experience from both sides, so I'll be happy to share my opinion here.
Right now I have a 7 month year old black american shorthair with a little white star on his chest.
His name is Buster, and he is of feral lineage. His mama was feral, and he lived the first few weeks of his life on the streets. I found him at about three weeks of age, and his mom had been (purposely) killed. He has been hand raised by my boyfriend and I, and lives entirely indoors. Despite his feral history, he has no interest in ever going outside. He's very healthy and happy, and has a little perch by the window. That's all he seems to want. We recently took him outside under our supervision, and as soon as my boyfriend knelt down next to him and set him down, he crept under his legs and leaned up against his knee and just hunkered down there and refused to leave our side. When my boyfriend stood up, Buster just laid next to his feet. I don't know if we just got an odd feral, but he seemed to have gotten enough of the outdoors when he was a little baby.
I've had a lot of indoor/outdoor cats and a few indoor only. One indoor lived to twenty and died of old age. My indoor/outdoor... We experienced a lot of problems. We faced a risk that many people don't even think about-- cats being stolen. Literally. I've lost two cats to other people. They removed their collars and tags and replaced them with their own. Alex and Little Miss Bee both were stolen from me. We need to remember what a risk people are. Not just people in cars, but people. I have heard and seen so many horrible things.. People are extremely cruel. They steal, torture, beat, poison, and shoot cats just for the fun of it. And they do the same to dogs. Unfortunately we still face this risk at times with indoor cats.
My neighbor was recently robbed, and when she went to her microwave.. She found her cat inside of it. I'd really not say anymore about that. It was terrible. People can really suck.
Another risk people don't often think of is cats becoming feral. I have a neighbor who owned six cats. Two of them were stolen at one point, but have since been returned. Two other ones were once 100% indoor cats, and then became indoor/outdoor. One day, they just didn't come back. When they found the kitties, they wanted nothing to do with them and were very mean and spitty and ran away. They had become too feral.
(I do live in Las Vegas, however, so it may be very different from other places... Indoor/outdoor or 100% outdoor is extremely common here, though. Very few people have purely indoor cats.)
I am totally for indoor with supervised or limited outdoor access, or 100% indoor living. I do not like indoor/outdoor or 100% outdoor. IMO, it's just not safe enough. But yeah. I just love my babies and I want the best for them, and I don't want them to ever experience the cruelty of people because I let them wander too far. And risks can happen anywhere, not just in cities.
I HOPE YOUR KITTY FINDS HIS WAY HOME!
I know the feeling of waiting for your baby to come back, so I understand. Don't worry, it is NOT your fault. I'm sending lots of love your way.