I have them right on the end, the bees stick them into place and I actually quite like the extra piece on the frame. It helps me handle the frames but I think I am the only one who thinks this
. It also keeps them clear of the rails as the extra height does cause problems.
I have never noticed the extra mm difference. Been using them for many years with no problem. I also quite like to use the colours, I use the red ones for frames that need changing, green for frames that need noting ( for example queen cells) and yellow for general.