Earned Schedule instead of Earned Value?

This presentation from PMI conference in UK this year describes the problems with Earned Value Management. One is that Earned Value is useful only in the early stages of a project for providing schedule management information - the SPI will always be 1.00 at the end of the project. Another is that most people don't understand schedule in terms of budget - and the use of accounting practices in project management probably has a lot to do with that!
The proposed approach uses the same basic information as SPI but expresses a Schedule Variance in terms of time rather than money. The SV(t) is the difference in time between the the status date and the date for BCWS equal to the current value of BCWP.
Earned Schedule