Sequências do Entity Framework Code First e do SQL Server 2012

IObjectContextAdapter objectContextAdapter = (this as IObjectContextAdapter);
objectContextAdapter.ObjectContext.SavingChanges += SavingChanges;

void SavingChanges(object sender, EventArgs e) {
        Debug.Assert(sender != null, "Sender can't be null");
        Debug.Assert(sender is ObjectContext, "Sender not instance of ObjectContext");

        ObjectContext context = (sender as ObjectContext);
        IEnumerable<ObjectStateEntry> modifiedEntities = context.ObjectStateManager.GetObjectStateEntries(EntityState.Modified);
        IEnumerable<ObjectStateEntry> addedEntities = context.ObjectStateManager.GetObjectStateEntries(EntityState.Added);

        addedEntities.ToList().ForEach(a => {
            //Assign ids to objects that don't have
            if (a.Entity is IIdentity && (a.Entity as IIdentity).Id == Guid.Empty)
                (a.Entity as IIdentity).Id = Guid.NewGuid();

            this.Set<AuditLogEntry>().Add(AuditLogEntryFactory(a, _AddedEntry));
        });

        modifiedEntities.ToList().ForEach(m => {
            this.Set<AuditLogEntry>().Add(AuditLogEntryFactory(m, _ModifiedEntry));
        });
    }

private AuditLogEntry AuditLogEntryFactory(ObjectStateEntry entry, string entryType) {
        AuditLogEntry auditLogEntry = new AuditLogEntry() {
            EntryDate = DateTime.Now,
            EntryType = entryType,
            Id = Guid.NewGuid(),
            NewValues = AuditLogEntryNewValues(entry),
            Table = entry.EntitySet.Name,
            UserId = _UserId
        };

        if (entryType == _ModifiedEntry) auditLogEntry.OriginalValues = AuditLogEntryOriginalValues(entry);

        return auditLogEntry;
    }

    /// <summary>
    /// Creates a string of all modified properties for an entity.
    /// </summary>
    private string AuditLogEntryOriginalValues(ObjectStateEntry entry) {
        StringBuilder stringBuilder = new StringBuilder();

        entry.GetModifiedProperties().ToList().ForEach(m => {
            stringBuilder.Append(String.Format("{0} = {1},", m, entry.OriginalValues[m]));
        });

        return stringBuilder.ToString();
    }

    /// <summary>
    /// Creates a string of all modified properties' new values for an entity.
    /// </summary>
    private string AuditLogEntryNewValues(ObjectStateEntry entry) {
        StringBuilder stringBuilder = new StringBuilder();

        for (int i = 0; i < entry.CurrentValues.FieldCount; i++) {
            stringBuilder.Append(String.Format("{0} = {1},",
                entry.CurrentValues.GetName(i), entry.CurrentValues.GetValue(i)));
        }

        return stringBuilder.ToString();
    }