The HM style runs 1 cup size smaller than the 3DM counterpart on me. I need a 70DD in the Ewa Michalak 3dm Margot (449) and in Ewa's padded plunges, but in the HM, a 70D fit me perfectly (70DD hat too much fabric at the upper part of the cup).
Apart from that, the center gore is quite high for an EM bra, but the overall coverage is pretty low (as expected in a halfcup bra).
The band runs snug - my underbust measures 27" tightly, 29" loose and a 70 band fits just perfectly. The closure has 4x2 eyes, straps are fully adjustable.
The bra gives a nicely rounded and uplifted shape, quite amazing for an unpadded bra!
The HMs by Ewa Michalak run very open on top, and the Ewa Michalak Hm Margot is no exception to that rule. Make sure you order one cup size down from your regular size unless you are super full on top - otherwise you'll end up with a bra that is wrinkly and more full-coverage than you like . This style is intended to be worn as a halfcup and it looks weird if it's too big.