Since the rifle squad thread seemed to be popular we'll try this.

For deliberate attacks and raids light infantry units are normally organized into three elements, not including the headquarters: support, security, and assault.

The tried and true light infantry TOE has been three plus one; three identical rifle platoons plus the weapons platoon at company level, or three identical rifle companies plus the weapons company at battalion level.

Would there be any advantage to organizing light infantry units into specialized support, security, and assault elements permanently?

This would mean the organization would be optimized for raids and deliberate attacks. Would that effect the organization's ability to successfully conduct constabulary type operations or defensive operations?

If you organized permanently this way at what level should it happen. Companies with support, security, and assault platoons, or battalions with support, security, and assault companies?

If not all light infantry units, perhaps just the ranger battalions?