>Sorin,
>
>That would work beautifully if the UI has a 1-1 relationship with the middle tier.

John,

For a moment I misread your message and thought you were referring to relationship between middle tier and data.
When you say UI (just to eliminate any confusion) you mean presentation, right? If so, then achieving the 1-1 relationship depends on how "granular" is the biz class design. Though, PMI, I am not clear why the UI would have anything to do with this.
The point I was trying to make was that the change tracking could be implemented in the middle tier.

Regards,