In my opinion, all the SCAR is, is a piston driven AR that was designed as a piston gun from the get go. Not an aftermarket conversion. Otherwise it is very similar to an AR rifle.
I personally do not see that the SCAR is worth the extra $500 - $1000 over the AR. Everyone I've talked to that has one loves them. They perform well. But it is still just a piston AR done right.
I would buy a high end AR instead and put the extra money into a nice optic or tacticool accessories.

my .02 worth.