Ease of sharpening seems to be in-between Cruwear and M4.
Wear resistance seems to also be in-between Cruwear and M4.
Corrosion resistance falls behind both Cruwear and M4,,,,But it may offer a keener edge so maybe thats the trade off. (Although both Cruwear and m4 get scary sharp as well)
I can't find anything on Toughness other than Crucibles website states that Cruwear has "Exceptional" toughness and REX 45 has "Good" toughness.
Knife center says REX 45 has "exceptional" toughness, but they also say Cruwear has "superior" toughness.
Given the recent sprints and how much I love Cruwear and M4 im not really sure why i went with 52100 other than the fact that I WANTED a patina in an easy to touchup steel.
If this one patinas well... well then my 52100 might be getting replaced.
But when comparing it to M4 and Cruwear im not seeing many improvements, Unless you compare it to 52100.
If only someone could find some info on the toughness.