We got five chocolate orpingtons this year, our first chocolates. Mine are all very dark brown, like 90% cocao. I agree with others statements, they aren't black as all black chickens I've had had an iridescent green in the sun. These girls are matte super dark brown.
I agree on body type too, ours are like yours. The chocolates are much more streamlined than I expected. They don't look like orpingtons compared to our waddly buff or the three new lavenders, that look like ruffled rainy cumulus clouds, super fluffy butts.
I'm hoping our chocolates puff with age, as I think they'd be adorable all floofy.