In general I haven't seen many good acne scar results from fraxel.

Fraxel re:pair is best in my opinion for wrinkles, while the re:store is best for acne scars.  This isn't to say that either is going to make significant changes in acne scars, but the recovery time for the re:store is much less, making it more worthwhile to get that than the re:pair given fairly equivalent acne scar improvements.

One comment or caution: Asian skin and lasers such as re:pair don't always do that well.  The reason is that pigmentation after this can be variable and that may lead to poor results, even if the scars are lessened.  This is another reason to consider re:store (or nothing) for this problem.