hold on, Warren, let's pretend for a moment that your HK quote is canon. That's the assessment of HK-51s when the HK factory is found, not when they're developed and produced (and eventually lost) alot of things can change in 200-300 years with a droid model.
Do you have an alternative source? If not, we can assume this is cannon, because, despite it being cut content, it is still cannon.
The whole point is that the HK-51s were lost for like hundreds of years and then found on Ilum....
You asked for my unbiased evaluation of the HK's battle effectiveness. I gave one. What's yours?