In the game, Gil was able to block multiple slashes from Excalibur using only the hands of his armor when necessary to fend off attacks aimed at his head.
Have any pictures or video of Seph destroying Shinra? Can't recall this little moment.
Here, at 4:23 he makes the top of the building fall with telekinesis, then at 4:32 he swings his sword at it making the portion of the building become debris.
The barriers would be screwed against Ea considering Gil was able to destroy Iskander's Reality Marble with it and can open dimensional rifts with its power output. Durability would mean jack squat as well against any anti-magic Noble Phantasm or Gae Bolg from Gate of Babylon.
Ah, yes, they would certainly be useless against Ea. And Sephiroth doesn't have anything that can defend against something of that magnitude. That's why I believe Sephiroth's advantage lies in his speed (specially taking his teleportation into account) and strength. He has enough speed/reactions and power to defend against GoB sword rain without much problems, though; GoB sword rain is a very inefficient way of using Noble Phantasms, as he isn't tapping into their full potential.