Thank you for that comparison.
Unfortunately there seems to be a misconcept regarding the terminology of dynamic range vs. exposure latitude. You've proofed that the Alexa has 1,5 stops more exposure latitude than the Helium but don't mix that up with dynamic range because these are two different things.
"Dynamic range is the range the camera can see from the deepest darkest shadows to the brightest highlights in the same shot. Latitude is the range within the dynamic range where we can expose and still get a useable image."