The comments were getting long and burdensome so I thought to start a new post on the same subject. There's still more to cover on this issue.
A few years ago I trapped a very pregnant female "feral" cat. I took her to be spay/aborted. She hated me for 10 days while I kept her in a cage. Then I released her back in the same place and didn't see her for 3 months. Of course, I worried about her all this time. I was putting feed out one morning and up she walks, pretty as you please, came over and started rubbing against my leg and purring. I can't being to tell you the guilt I felt. She did get a nice home after that.
And she was one of the reasons why I feel TN&Release is so cruel. I would have to say that my experience has been that nine of ten "feral" cats I have trapped have come out of the trap friendly. It is difficult finding them homes, however, because there are so many cats out there. But I tried and did with very few having to be put down. I will not adopt out cats that are FiV positive.
And on that note, I watched a colony go down within two weeks of each other, about 15 cats. Vet ran tests and found two of the cats were FiV positive, so we assume the others were too. Since they shared water and food bowls, it is a good assumption.