I have a Downy ball, use it occasionally if/when the urge hits instead of the agitator-mounted dispenser. I even use non-Downy softeners with it, and the ball has yet to explode from the "misuse." N E Ways, I sometimes have a bit of concern about how well the softener rinses out of / dispenses from the ball, but haven't seen any obvious evidence of malfunction. I have noticed a few times that very thick liquids didn't rinse completely out of my Calypso's dispenser.
Also, the last load of shirts I did (a BobLoad® for sure), I intended to add Downy Advanced manually and missed it. Not wanting to run another rinse, and also as an experiment, I let the load go, and I could definitely tell the difference on the 100% cotton and cotton-blend items. They weren't too bad after hang-drying (300 RPM spin) and then a 20-min dryer run, but clearly not up-to-par of Advanced use.