I think so. Also it won't be very simple to convey to new users.

> so that behavioral drops don't have to be the first step in the exclusion process (having the process be order sensitive sounds bug prone to me)

Wait. you want some sort of dictionary indexing where the int refers to the filtered events. Mind-twisting ....
I fear you still have a point here, Tal. If we drop epochs and do whatever you want to index [14] and get what you believe is trial 15. If the trial was dropped you want to get an error saying that this trial was dropped?