I am a level 16 Titan and I find that, while most Titans get used to their defense stat, it doesn't help in pvp. And you never know when a hunter has blade dance on. so generally, i stick to the back of the pack and take out the people who come up behind OR if in control, i go for their furthest point as soon as a large firefight ends, because they stop spawning then, and then i stick up my shield and take the point.