Ben,
I am a novice user but what impresses me about the Imposition features is how the data sequences through the positions.
Let's say you are printing 100 cards with sequential numbers 1 ~ 100. If printing 1-up, you will get a 100-page pdf with a unique number assigned to each page. If you print 10-up, then you will obviously get a 10-page pdf but the data is sequenced across the 10 positions.
When I used to do this sort of task in Indesign or MSWord, each position would need its own data set. Position 1 would print the dataset [1,11,21,...] and position 2 would print dataset [2,12,22,...] and so on. This requires more data work because the data must be pre-compartmentalized.
Assigning how the data flows across positions is crucial to planning how the sheets will be finished.
Matt Louis