Maybe I'm just used to the phone behavior, but it requires a lot of momentum to swipe away tabs on the tabs panel. Can the behavior be made more like the phone implementation? e.g. if there's any momentum to the right when I swipe right, the tab should be removed, rather than having to exceed some threshold. Anthony, any thoughts?

I filed bug 1178794 to follow up on the feeling of this interaction. But, specifically on the "threshold" aspect, I think it's good to have that. It's pretty standard behavior with these types of interactions and it really helps avoid dismissal errors (which can be pretty bad, even if we have a toast).