I have a question.<SNIP>
I was wondering what others think on this.
To me, that is a great time to call for Situational Awareness: Combat skill checks, to determine exactly what they notice in the heat of battle. If they get an Amazing result, perhaps they do see which one is firing at them.
Otherwise, I also like to go against RAW in this; it just seems as though the rule is for a 2-second or less combat round, not a much (MUCH) more abstract 10-second combat round. So, once I started running RM, I allowed the players to use OB to defend against any attack they were aware* of, with mods for positions and such.
*It would be down to the Sit Aware: Combat check.
For the Hasted TWC monster situation, I would treat it like they were being attacked by more than a single opponent. I mean, really, if someone is going to go through all of that trouble.... But more seriously, the speed at which they are attacking has to affect their targets defenses somehow. (Unless, the defender also got Hasted, then it would be back to normal, as both combatants are on the same "playing field.")