This has been hinted at in a number of the other replies, but not stated in plain, simple English. The wingnut operating the machine is the most important safety device, bar none, and in the absence of safe gun handling any other "safety" only prolongs the inevitable -- an accidental discharge, and quite possibly much worse.
Regardless of the type of weapon involved, the type of shooting being done, or any other circumstances, safe gun handling ought to be any shooter's first and foremost priority, with any other consideration -- PC, getting a shot at a t-rex-sized buck, winning a match -- so far back in second place as to be irrelevant. If this, that, or the other mechanical device improves your feeling of being safe, great, use it -- but don't make the mistake of substituting that device for proper handling of your gun.
That said, I prefer half-cock for both sitting and moving, with my flinter or caplock.