My cats all wear (breakaway) collars because I am afraid of them getting out. Some of them are VERY interested in the door when people go in or out, or especially when we let the dog in/out and not everyone in my house is as careful as I am about the doors with the cats. They are microchipped too but I think the collar shows people that they are not just another feral cat and makes people more likely to try to catch them. We have a lot of ferals in my neighborhood. I've had one cat get out once when a family member was letting the dog out, luckily I was able to run out and he stayed on the porch so I just picked him up and brought him inside.
I was worried about the collar marks because a judge at one of the shows I went to commented on one of my cats having marks from a collar. She said I should stop using it or the marks would become permanent. Since then I started taking the collars off at night of the two I planned to show, since no one was using any doors at night. I also bought a new type of extra-soft collar which is supposed to NOT break the coat or cause rub marks. It's made for show dogs but it seems to be working so far for the cat. It is made with super soft material and no stitching or seams on the inside so that there is nothing rubbing against their fur.