Pessimistic is the most secure, but you run the risk of someone begining an edit then walking away locking everyone else out on the network. Optimistic locking is a better idea. The record is not locked until you attempt to save changes. If someone else on the network made a change while you were editing, you can trap it. The Developers Guide has some excellent examples of conflict resolution and other multi-user issues.

IMO, you should always Table buffering, so if the record pointer moves, you don't automatically update the underlying table.

Charlie