Not really, since ultimate rank canister bomb does so much DPS heavy lifting.
vit -> fire conversion is the better one, IMO, since pierce makes up so little of bat’s flat damage. For fire builds that want to get in on the scales meta, doubled up blazeseer signets is how to go about it. Those setups will have less raw firepower though. If you want to try it, take a look at Ya1’s sorc for Devotion pathing.
If the heals aren’t enough for you on JS’ setup, you might try pumping points into either Haven or Resilience, since the % Healing increase will roughly equal out to the same % in damage conversion.