I wish this sapper worked like this:

+ Instead of stunning and slowly destroying a building, this sapper converts the sapped building to your side.
+ Enemy Spies cannot sabotage a converted building.
+ Engineer that owns a building that has been converted cannot remotely destroy it.
- While sabotaging and before the conversion happens, Engineers, Pyros, Heavies and Scouts can remove it with their melee.
- Building is destroyed in 12 seconds (or less) after converted.
- Converted building takes more damage from foes and has less attack power.

Hoping that this sounds nice and balanced.