Okay, I thought this was already answered before but I couldn't find it anywhere in the official thread of FAQ, so I'll ask here.
Do multiple uses of Boost with the Restorative flaw function like Healing does?
Baseline Boost says that it does not "stack" with other boosts. Very simple, if you have Boost 4 you can't boost twice to get get +8 to whatever. You can Boost again to get any faded boost back however.
The Restorative flaw seems to change this however. Since you can't actually boost anything and their is no lingering affect fading away. If you use a Restorative Boost 4 to restore 4 points of lost Dexterity or 4 ranks of a power... there does not appear to be anything for a second application of that Restorative Boost to stack with... as Restorative Boost is truly instantaneous and leaves no lingering effect to be stacked with. A second use of Restorative Boost 4 thus seems not to be stacking with any prior boost but instead merely restoring four more points of lost ability/power/whatever. In other words, as the question asks... its seems to function more like the healing power (and a character can benefit from multiple healing applications).
Now, the whole issue behind this question is in regards to suggestion to give a character's Ablative Protection a regenerative capacity. Basically the ability to restore a single point of lost protection each round that the user rests. That doesn't seem signifigant enough for an Extra, as the resulting effect would still be by and large completely inferior to normal Protection. Moreover it feels very much in line with several of the 1pp Regeneration options and is seemingly equivalent to having:
Boost-Protection 1 [Extras: Reaction (end of each round); Flaws: Personal, Restorative, Limited-Requires Rest] again 1pp... but then again, normally Boost does not stack. However, as noted, the reason behind Boost not stacking does not seem to apply to Restorative Boost effects.