If your palomar was breaking, a different knot wont help.
Try, in this order:
-Making sure all knots are tied properly and securely
-Moistening knots before tightening
-Using fresh, new line
-Making sure your line can handle the fish and conditions in which its used
-Using high quality hooks, and checking each one for burrs inside the eye
Also be sure to check periodically for line wear.
I dont like dropper and other multifly rigs because I'm wearing them and untangling them as much as i'm fishing them, but knots breaking during dropper fishing is a problem that may soon effect all other types of fishing.