What are the advantages of the boring bar and carbide insert over the end mill you ask?
When an end mill dulls, it has to be replaced and thrown in the "to be sharpened" stack. When a new end mill is installed, the depth of the end mill has to be exactly where the last end mill was removed from. If not, the die cutting depth will change, and as such, the die will have to slightly be raised or lowered in the tool head to accommodate this change.
With a boring bar, when the carbide insert dulls, all that has to be done is to remove the Bosch motor from the trimmer adapter, remove the TS6 screw, and either rotate to a new cutting edge (there are three) or replace the carbide insert. Reinstall the motor, and verify that cut length hasn't changed.