Difference between SavingChanges event vs SaveChanges override?

I've read multiple posts about how to implement an audit log using entity framework. I currently have the audit logic embedded in the SaveChanges method in the DbContext. Please keep in mind that the code below is an EF4/5 implementation and I'm preparing to update to EF6.

namespace Database {
    public class AuditDetails {
        public string RemoteHost { get; set; }
        public string RevisionUser { get; set; }
        public string RevisionNotes { get; set; }
        public DateTime RevisionDateTime { get; set; }
    }

    public class MyContext : DbContext {
        // ... Unrelated overrides here ... //
        public void SaveChanges(AuditDetails auditDetails) {
            var saveCount = ProcessConcurrency();
            var items = ChangeTracker.Entries<MyEntity>().ToList();
            if (saveCount <= 0 || items == null || !items.Any() || auditDetails == null) return;
            foreach (var item in items.Select(entityEntry => entityEntry.Entity).Where(i => i != null)) {
                // ... create audit log using AuditDetails values ... //
            }
            // ... and call base.SaveChanges() ... //
        }
    }
}

So the questions would be:

• Is there a benefit to moving this to a SavingChanges event handler? Or possibly split the functionality to use both?
• Does the AuditDetails information preclude using SavingChanges?
• I do not have an override for SaveChanges that accepts the Boolean argument for use in transactions. How would adding that change the solution?

In Summary:

• When would you override/implement SaveChanges and when/why would you prefer to use a SavingChanges event handler?