Yannick do you say too close b/c of the user being clear as to which one they are clicking on? If so, maybe on mouse over a box makes it more clear. So as you move your mouse along, the box makes it clear which one you are on. Or a shadow box like how Pinned Tab icons work (that would be more consistent)
(Box exaggerated here for effect)

As I stated, for me, I would like more icons to show (closer together). I only got this screen shot by widening, normally I just see dots. (At the same time, I am trying to cut back on Saved Windows)
I would like to not have the "+" icon in the same vein.
This is a really good new feature, I like it a lot!