Sidi Mega

So I’ve been thinking of getting some of these for my fat feet.
Two questions:

  1. is the “mega” actually on a different last (diffferent size carbon sole) or is it Giro HV style where they simple put a larger upper on the sale exact shoe?
  2. Does Sidi change their last on the 1/2 size or the full size (ex: 42, 42.5 are the same, 43 is larger OR 42.5/43 are the same, 43.5 is larger)
    Thanks y’all.

I have a pair of genius regular and genius mega and the sole on the mega is about 5-6 mm wider.