Looking through the forums i've found a couple of mentions of Client side updates for concurrency control rather than using triggers or the timestamp functionality. The following post is pretty much what i was after (except i'm planning to use a date field called 'LastEdit' for auditing purposes):

http://www.llblgen.com/tinyforum/Messages.aspx?ThreadID=977

public override bool SaveEntity(...)
{
   // Updating an existing entity
   if (!entityToSave.IsNew)
    {
        IEntityFieldCore leField = entityToSave.Fields["LastEdit"];
        if ((leField != null)&& (!leField .IsChanged))
        {
            leField.SetNewFieldValue("LastEdit", DateTime.Now);
        }
    }
    return base.SaveEntity (entityToSave, refetchAfterSave, updateRestriction, recurse);
}

How does the above code work when saving an entity collection? I've been able to override the SaveEntity and set LastEdit for individual entity saves but how do you set fields when using the SaveEntityCollection method?

Also does this have an advantage in that the concurrency field does not have to be re-fethed from the database so it would be (slightly) more efficient?

SaveEntityCollection traverses its collection it gets and calls SaveEntity on each entity which has to be saved. So overriding SaveEntity will be sufficient as that's the only part which actually performs a save

Also does this have an advantage in that the concurrency field does not have to be re-fethed from the database so it would be (slightly) more efficient?

You mean, you first fetch the last date, then update it ? I'm not sure if I understand what you mean exactly.

Otis wrote:

SaveEntityCollection traverses its collection it gets and calls SaveEntity on each entity which has to be saved. So overriding SaveEntity will be sufficient as that's the only part which actually performs a save

Thanks for that, i was looking the wrong place (as usual )

Finally got it working, my final code for anyone who's trying to do a similar thing:

            public class ConcurrencyFilterFactory: IConcurrencyPredicateFactory
    {
        public IPredicateExpression CreatePredicate(ConcurrencyPredicateType predicateTypeToCreate, object containingEntity)
        {
            IPredicateExpression toReturn = new PredicateExpression();

            IEntity2 entity = (IEntity2)containingEntity;

                switch(predicateTypeToCreate)
                {
                    case ConcurrencyPredicateType.Delete:   
                    case ConcurrencyPredicateType.Save:     
                        toReturn.Add(new FieldCompareValuePredicate(entity.Fields["LastEdit"],null, ComparisonOperator.Equal)); 
                        break;
                }

            return toReturn;
        }
    }