I think it's great that Luis no longer occupies a spot in the trek, allowing you to recruit Tim Timster more easily.
BUT: after dismissing Tim Timster, Luis ISN'T dismissed, which I think story-wise is a bit strange. And it gives you an extra unit, with a free spot in the trek.
Luis isn't the most useful character, but a free extra die in combat, plus added cannon-fodder seems like a bit of an exploit to me. Especially since Tim Timster is often introduced at the start of a game.