Perhaps you should start with the 13 kata? There are less movements but the variety of the movements is greater. The 31 has a ton o' yokomens.
Aside for those of you in the NYC megalopolis:
O'Connor Sensei (no relation other than being my teacher) is hosting a Kumijo seminar on 3/12/2005 @ ACNJ - Morristown. Sensei hopes to cover the 10 forms. Familiarity with the basic jo suburi is a requirement. Call for info. http://www.aikidocenters.com