Question: does the enhanced payload, regardless of the size of the bombs..mean that the bomb-bay doors are deployed longer, which then makes the B-2 visible on enemy radar, and thus more vulnerable? This would NOT seem to be an issue over Afghanistan, for example... where the new technology is an obvious force multiplier, because there is no threat to the B-2 from the ground..but sending the plane over Iran, to target scattered nuke sites...well, if the plane is unstealthy five times longer than before..( am I correct in assuming it would take 5x as long to eject 5x the # of bombs?) there would seem to be much greater risk to the aircraft..
They would rarely drop them all at once. And those rotary racks can spit bombs out really really fast.
I would think they would open and close the bay to drop them in small batches for different targets.
I don't think that there will be a significant threat to any aircraft flying over Iran after H+30 minutes. At that point their Air Force and Missile defences will be quite similar to that available to Afganistan.
While it might be somewhat longer to drop 5x as many bombs, they wouldn't generally be dropping them all at the same time. They'd pop the bay doors, drop one or three, pop the doors shut and go on the next "recipient" of their eggs. Thus they would be vulnerable 5x as long, it would not increase their overall vulnerability much, since each would be a separate "event" for the defensive systems on the ground.