I have Sidis in a 40 mega and got size 40 Dromatis.
The Dromatis are ever-so-slightly longer and have a roomier toe box. Feels like better arch shape for me too. The laces are firm and the soles are wonderfully stiff.

I've been complaining about my Sidis just a little bit, because if they were leather instead of Lorica the toe box would have formed to my foot.