Hi,
I could not agree more...
The risk of shallow water blackout is real, and this is true for any rebreather. I don't believe that rebreathers are dangerous, once risks are known and mitigated.
At the end everyone choses the level of security that he wants... but as far as I am concerned I would not dive any rebreather (except. my O2 rebreather

) minus at least 2 independant ppO2 meters.
Should those meters "disagree", I'd thumb the dive and bail-out to OC. Period.
Kind regards.
Cyrille