Do the abilities/equipment gained from the DLC make the final mission too easy and underwhelming?

Consensus seems to suggest playing the DLC before the final mission, but I'm a little worried doing so will suck the tension out of the final fight by making it too easy. I'm not really planning to do a NG+ run though, so I'm wondering if doing the DLC after beating the final boss will leave me with enough content to actually play around with the stuff the DLC gives you.