you don't have to own a pair of something to know what they're about.
in this case it helps since not all jeans stretch/fit the same.
anyway, i went my usual size 32 in a pair of the raw blacks and they were pretty damn tight to start with but after about 10-15 wears they are fitting very nice.
As for stretching they stretch a lot less than any other jeans i've purchased. the indigo denim imperial uses stretches more/quicker than the black.
from pics i've seen of your build i wouldn't size down (not saying you're fat, just not stick thin like a few guys on here) because the thighs on these are pretty tight.
in all honesty i would recommend going your usual size - it will give you a good balance between getting a slim fit and having a pair of jeans that won't cut of circulation to your legs. the raw blacks really don't stretch a lot like nudies and such. even for me going my usual size i could hardly get the top button done.
i think ppl say these run a size small because most jeans actually run a bigger measured size than the tagged size. i reckon these do actually run true to size.
either way they are awesome jeans. not only the denim but the construction is amazing. take a moment to go over all the seams, edges etc to check the effort that's gone into them to make them so tidy. i know i'll be picking up a pair of the dukes in indigo soon as well