If you do this, you'll have to make sure the N-Up rows have a fixed height.
There's a problem in all versions of PB where an embedded N-Up with Autoheight fields and detail will only return the height of the LAST detail row to the container object. If row in detail #1 of the N-UP is 200 high, but row N is only 100 high, the container object gets sized to 100, and cuts off anything from the other rows.
http://www.pchotshots.com/bmettee/nup-demo.zip contains a PBL to demonstrate. (I've been trying to get this fixed for years)