If the heavy's DPS being 30% faster is enough to make that difference, yea, sure. It's a rather specific circumstance and has to be weighed against the armour emblem's own value though. Even armour emblems, as crappy as they can be, can also make their own significant difference in certain circumstances. It might only end up being a 7% damage reduction or whatever, but it's hard to get a Chieftan or a Conqueror to 100% damage reduction without one and the difference between 93% reduction and 100% reduction when a high level Zoya or GW Tiger is hitting you with their 400% damage skill while you've saved your Chieftan's skill for that moment can be surprisingly big.