It seems to make it wider. It's a Cone shape so the farther away, the wider the area is.

However the real choice is based not on the size of the area, but if you group or run solo. If you play mostly solo, then pick the one that gives you a larger area, if you tend to group then pick the one that benefits the allies around you. There are a number of skills in the Nightblade line that have a choice between helping you more or helping your allies more and you the same. If no one else is around, why help them? If there are others around, do you want to be selfish? Those are the real questions to ask.

You can also respec just your Morphs so during the PvE leveling part of the game you can run with the one that gives you a larger area, then change the Morph for PvP and Group Content like the Undaunted stuff. So, build them both out and swap out as you need to.