This is definitely something we would like DirectRT to do. Unfortunately, DirectRT does not have a function yet for displaying calculated variables the way MediaLab does. It is something we are working on for the next version. We hope to implement it in a similar manner to how MediaLab uses the responses.xls file for its Advanced Features.
So let me just throw that out there also--you could do this MediaLab but the RTs would not be as accurate as they would be in DirectRT.