Sidi 5-Pro and Lorica.

I was in need of new cycling shoes, so I decided on the Sidi's Genius 5. Found one for a good deal. However, I didn't really look carefully (that's my fault), and realized that these were the older version of Genius 5-Pro. It has the Millennium II sole instead of the Millennium III that the 5-Pro has.

It's never has been worn. So, I'm wondering if those who had both, is it really that big of a difference? I'm not that fast nor a racer (aside from Triathlons), so I'm not sure if that makes a difference.

Thanks