I'd say none. People say this is "bannable" sure you CAN be banned for using this, I used it for a long time still not banned!
Honestly, If you are scared of being banned it's not worth using, it's not much of an advantage. Only useful moments were for spawnpeeks because the leaves on trees turn invisible, you can do 1-second kill in Bartlett.
The downside is that the difference between Castle and the normal barricade is not readily apparent. And if the enemy happens to have the same colored clothing as the wall behind him... you gonna have a hard time seeing him.