I know I will get hit here....
We have 8, 6 that go outside, ONLY during the day. At night the doors are locked(we have a cat door by both the "human" doors) Everyone is in at night.
Satin, our oldest is going on 15. My husband has always treated his cats this way. We have lost one this way, tho to be honest Homey was never in the best of health from day one. My husband believes in letting them live life to say.
Now that said, if yours has been an indoor cat all his life, no I would not let him outside. We have 2 here that will not go out. Squirrel is terrifed of the outside(seeing how she was more then likely kicked out of the house and ran off) she is one of ours-we found on the side of the road-ones. The other is my husband's mother's cat whom we inherted as we promised my MIL we took her in when she passed away. Precious has no front claws and should never go out.
I have one that only comes in when it rains or it is time to come in. The others come in, check on us and go back out.
You ask, do we have cat fights bite problems and other problems. Yes. we keep albon on hand for the cat bites. It is an anibotic that helps keep the pus from building up from them. Our only bad one was my Figgit who decided to go out AFTER a rain storm, climb a tree and FALL OUT OF IT!!
Like one of the other ladies, over $600 later and a broken skull, well she goes out now, but no tree climbing anymore. she got fat and sassy instead. BTW, the vet gave her less then a week to live. When we came back for her check up 2 weeks later, he was both surprised and pleased she lived through it. Tho, I won the bet at what happen to her, vet's vote, car,, my husband's vote was a bb gun...and I said she fall out of the dang tree....
We live in a rural area and that makes some different, tho if you have coyote anywhere near you, cats beware!