Yes. It's not a rigid down-to-the-tenth-of-a-degree kind of thing.
As for retention, I'd note that the basic version of the high ready I do, with the gun at about a 45-degree angle in front of me, was originally developed specifically for being in and around crowds of hostile people and -- if done properly -- provides both protection against gun grabs and an obviously quick return to "the two" when necessary.
Candidly, I'm hard pressed to believe that any ready position is foolproof when we're talking about literally slaloming our way past a huge number of unknowns.