The things that primarily motivate me for a change in position are discomfort or pain. If I were in competition with other bicyclists then power output would be a motivating metric. Certainly it would be wise to choose a cycling position that will not cause chronic or acute injury. How long have you been heel-up pedaling and was this time period all without discomfort?

In my opinion making a 2.5 centimeter change in saddle height at one time is excessive.