I bought the Benjamins but ended up returning them.
Pretty much the Benjamin is Orages attempt to make pants that are similar in cut to M6 and Holden. And I would warn you and say that the cut is really funky on them, like the ass and crotch section sticks out funny and the synthetic material feels really weak.
But as far as the sizing, I'm 5'5 and the medium was baggy. And now that I think about it, the sizing is pretty similar to M6 pants, except i think M6 runs a bit bigger.