Is scarring a side effects with a higher intensity laser beam?

Yes. Scarring can occur with either the Fraxel Re:store or Re:pair laser but there is a higher chance with the latter. Scarring may be red thick raised or depressed scars. This is rare but no physician can guarantee that scarring won’t occur with chemical peels, dermabrasion or laser resurfacing of any kind.

Both Fraxel Re:Pair and Fraxel Re:Store can do an excellent job of smoothing out scars, making them less noticeable or even invisible. They have very few side effects and have been proven safe by the FDA and by years of use. Re:Pair is a stronger, ablative CO2 laser and will work in one session. Re:Store is gentler, non-ablative and will probably take several sessions to remove your scars. 
In the hands of an expert, neither Fraxel laser should cause scarring. During your consultation with a board-certified dermatologist, your skin will be evaluated for texture, tone and color so that the correct laser and settings can be determined. Side effects for Re:Pair include a reddened face that may feel tight for up to two weeks. Re:Store generally has no side effects at all. Some peeling or dryness may occur for some patients with either laser. Please find a board-certified dermatologist to find out which Fraxel will work best for you.

If Fraxel Laser Treatment done properly for acne scars, Fraxel Laser Treatment should work great and shows good result.