This is one of those topics that has a tendency to set some people off. I know the SEALs jumped all over the high ready and then Blackwater began teaching it to their guys prior to deployment overseas. Later, Special Forces CIF teams adopted the high ready technique as well. As one SEAL described it to me in the past, the high ready is great because it is impossible to shoot your buddy if you have a Negligent Discharge. I have to disagree with this mindset for two main reasons.
The first is that ND’s happen because shooters get sloppy with safety measures and unit Standard Operating Procedures, whatever those procedures may be. You can zap your buddy if you are half assing the high ready just as well as if you are half assing the low ready.
Second, if your main concern as a tactical element is not having an ND and killing your own team members, than you have other priorities you need to work on. If your goal is to enter and clear rooms, maneuver to contact, or whatever the case may be, than your team needs to be tactically oriented towards accomplishing this task rather than oriented towards real or perceived safety considerations that have now became your main effort.
For those who are still unconvinced, here are a couple videos from real Subject Matter Experts:
Next subject, high ready vs. low ready with a pistol. What do you think?