I have recently bought a "Shoulder Collar" like this:
http://www.gollygear.com/shldr_col.h...FQVrKgod8F12aw
for Charlee...and I love it! It fits her really well, is made of very soft, light leather and she doesn't mind it at all. I was having some issues with the other step-in harnesses as at 5lbs she was able to get out of them. I had also tried a Buddy Belt, but I found it was breaking her fur. Of all my "trials" ( I have a bit of a harness/collar/leash fetish...constantly looking for the newest or most "perfect" one)...it is the one I like the best. Currently she wears it all day, and I only remove it at nights. Doesn't seem to causing any discomfort or problems with her coat.