The only mileniums I heard off that tend to crack are the milenium ICE - transparant blades. But I heard that OMER has fixed that already.
I have milenium green and so far although there are a few stress signs, and they might have lost some stiffness, they are ok, and I have no fear of breaking them just yet.
I bought milenium competition BLADES yesterday at a most amazing price: 16euro, or even a bit less. I just couldn't skip the oppertunity (it was the last day of a crazy sale).
Being able to seperate the blade from the footpocket is making the most of your money if you ask me. Therefore I'de go for OMER or Sporasub, not Cressi.
It also helped me a great deal backpacking with them for a few months.