Yea you can just install a straight up diff unit, but that gives you pretty much a direct drive setup. The slipperential would be a nice addition which would give you better setup adjustment capabilities, and some protection for your drivetrain.
Sounds good ! without it you'd have to be close on the setup or have a really good esc and packs to handle voltage spikes or binding drivetrain. This would be nice in a racer or extreme basher. don't think it would fit in my flm tranny forward chasis so if i break more than a few times i may have to look into a kershaw because of my chasis.