Since you're going to ask...

The weight of the Scar's bolt carrier is significant and results in a "forward recoil" effect (similar to an air rifle) which has been damaging optics. Hardened optics like current ACOGs and Night Forces haven't been damaged. Apparently, Elcan Specter DRs are good to go as well.

However, I wouldn't recommend a traditional Leupold, EoTech, Aimpoint, Accupoint, etc.

I've not personally experienced this, but have been involved in enough discussions with people who have (including pictures of dead optics) to believe it is a real issue. Also, .gov now only issues Specter DRs with the Heavy. This probably lends credibility to the issue since they would be hard pressed to find a more expensive option.