I tried a collar once on Jackson, but he chewed it to bits and plus I was worried about his neck. I only use his harness now and wouldn't try a collar again. I agree that with the trachea issue, it isn't worth fooling around.
I do wish his harness didn't mess up his fur, but I just don't keep it on him when we are inside to avoid that problem. Now that I've seen those adorable outfits Connie makes, I want that instead!! Gotta get him a vest! And the dresses are so darn cute, it makes me want a little sister for Jackson even more.