Which powers are affected by increased "Restoration and Defense"?
Solution 1:
Health Regeneration and Shield Regeneration are not affected by Power Restoration and Defense.
It's reasonable to assume that other stats that affect health or shields but lack the Restoration keyword are unaffected as well.
I tested whether or not Regeneration was affected via the [Team Support] power with [Rank 6 - Life Support] by monitoring my health changes directly through Cheat Engine.
Swapping from [Rank 4 - Squad Offense] to [Rank 4 - Support] did not change the amount of health I regenerated at all; deploying my [Assault Turret] took me from 200 HP to 290 HP every time.
The Defense keyword is probably intended to cover both Damage Resistance and Damage Reduction, as it doesn't seem to actually match any other existing stats. Unfortunately this is very difficult to test as the game simply does not provide enough information.
I'm not convinced a skill like [Backlash] is covered by the Defense keyword despite what the gosunoob article claims, though the [Rank 6 - Shield Resurgence] upgrade is covered by the Restoration keyword.
Unless you're constantly using powers like [Charge] or [Energy Drain] that explicitly grant some form of Restoration, the Power Restoration and Defense stat seems useless. I suggest avoiding it unless your build revolves around powers like these.
Solution 2:
It means abilities that restore shields or health are increased. e.g. If your ability restores 100 shield, it now restores 120 shield if you have 20% Power Restoration.
Solution 3:
Been playing quite a bit, but haven't delved into numbers so much. So, this is all "educated guesswork".
Defense. There are powers that lower enemy defense, and it seems to cumulatively increase the damage they take. That being the case, the boost could go the other way for power restoration and defense buffs.
Power Restoration. Seems to only apply to powers that directly increase shields. This does NOT seem to apply to Heal over time effects like regeneration or passive shield recovery. So, only powers like charge and energy drain that provide an instant boost to shields seem to be affected. As these are already large boosts that get up to or near 100% and there is no real "overcharge" for shields...the effectiveness seems to be negligible.
As there are no real direct healing effects in the game, I have started to opt for whatever option is given as an alternate to pwr rest & defense. This seems to be a better investment of points, even for my "tank" builds that use charge, backlash, & energy drain to wade through fights on legendary without bothering with cover.
I am curious to know if damage reduction improves backlash's performance, as my multiplayer asari sentinel seems to get way more service out of her lvl 3 backlash than even my legendary single player tank. My sp char is using shield capacity over damage reduction (mostly because charge and energy drain give percent of max shields, so sick). Things almost never touch my health anyway, even toe-to-toe with berzerkers and titans, but I'm curois if dr might end up being overall better than max capacity.