The CO2 ball discharger is a great tool. I think all ranges that have a reasonably large number of muzzleloader shooters should have one, just so you don't have somebody behind the firing line monkeying around with a loaded gun. If you aren't part of such a club, by all means get yourself one.
I feel range rods teach shooters bad habits, that can result in accidents. Shooters find themselves loading with one long fast stroke of the metal, of fiber, rod, that is dangerous when you switch to a wooden rod, because they can break and go through your hand. They teach shooters to holding the rod on the very end, that usually has some sort of knob on it, which with a wooden rod is dangerous, for the reasons previously stated. The single stroke loading can also generate extreme heat that might cause a discharge.
Now having said all that, I think a range rod is great for pulling a load with a ball worm, and for final cleaning before you store the gun.
Hungry Horse