My first time posting here after a long absence.

Here's my take on the difference, starting with the Razor Edge. There are two choices for draw weight ranges, 20-29 lbs and 50-60 lb. It's possible that the Razor Edge might go a few hairs below 50, but not many.

The previous Edge has ranges of 20-29, 30-40 and 40-50. If you start with 40# limbs, you could change them out later for a mild cost (if the parts remain available.)