I have had my character's holy symbol incorporated into my shield, but recall, if you use one function of an object, you usually lose the other function of it for that round. E.g. Shield Bash. Without the improved shield bash feat, if you use your shield to bash, you lose its AC bonus.
DM rule was, if you have your holy symbol incorporated into weapon or armor or shield, if you use your holy symbol to, e.g. channel positive energy, you lose the other function of that item for the rest of that round. I'd put it in the shield, not the armor, especially if what you carry is a low-AC buckler.
This may not be RAW, but it feels consistent with the general theme of things like Shield Bash and gauntlets.