If much of your sailing is pinching upwind & sailing deep off the wind than an AO is huge. The AO allows you to trim your sail to the apparent wind when sailing up & down wind. On beam reaches an AO can help you trim the sail in changing/gusty winds.
If you use more than one sail on your boom you have added hassle to rigging. Depending on placement it can get in the way during jibing. Adjusting it on the move takes practice.
The choice is yours.