I use about 2 oz of chocolate malt in my American Amber and I think it really adds a touch of complexity to the flavour and certainly it adds a nice colour. I wouldn't make mine without it. But, if you only want the colour, just add it at the end when you start to lauter. You'll get a nice colour addition without the flavour but like I said, I really like the flavour. Mine is simpler, just 2-row, C-45 and chocolate. I've also subbed out half the chocolate and added C120 in its place and it was nice, more raisin/prune characteristics which I liked but may not be "to style".
I'm certainly looking for the depth so i think adding it would be a nice benefit. I like the idea of C120, but like you mentioned it may not be to style. I think that would be great in a beer that is more of a sipper. I love the raisin/prune flavors, but they weigh heavy on my pallet.