There seems to be a lot of confusion over which model is best -I would argue it depends on your organization’s culture, the business model and strategic planning process..and who controls the purse strings.
ROE I feel can be a tough sell to many parts of the business – but from a Learning Experience Design point of view, it is a more learner centric as it the focus is on expectation and performance over concrete dollars and cents.
This is an interesting Slideshare powerpoint that illustrates in case study both ROI and ROE.