I have the same query as well. I have three pieces of vanya healing gear (approaching 4th piece next week when I farmed enough animal fat for the vanya beeches). I was wondering, should I put savage aim materia on them? Is there a soft cap or any kind of cap for crit, which as some point I would need to stop getting crit and go for something else?

P.S. I intend on getting full vanya, and getting full DL accessories.