Damage from hacking enemy portals

Our local smurf never seems to be able to get his desk portal above Level 5^*, so being the helpful Enlightened agents that we are, we've captured his desk portal and bumped it to Level 6. We've deployed a Very Rare Shield, Rare Shield, Force Amp & Turret onto it.

Now according to this reddit post adding the Turret increases the chance that they will get hit for double XM damage (critical hit), as well as increases the chance that they will actually get attacked when they hack the portal. The Force Amp doubles that damage done by the portal. I'm assuming that the Force Amp will stack in a multiplicative fashion with any critical hits so he will actually be hit for 4X damage by the portal.

According to the values in the JSON posted here (scroll down to portalHackEnemyCostByLevel) it costs 300XM to hack any Level 6 portal, but it doesn't specify how much damage the portal will attack with, the chance of an attack occurring, and if the damage is augmented by the FA/T combo. The last one, I'm going to assume is true, it doesn't make sense for the FA/T to not increase the damage done to the player.

My question is, are there hard numbers on how much XM damage a portal will cause if it's hacked/attacked and how likely it is to actually attack? I'm trying to work out if it's strategically advantageous to let his portal stand at Level 6 and only let him hack it 4 times, taking increased damage each time, or if we should get him to destroy it (by fielding off it), and rebuild.

_{*(cough, no teamwork, cough)}