I have been doing a lot of variance work of late and its difficult to show variance very easily on the current chart offerings. Can Phocas please look into adding a new chart type which you do have available which is called a Area Spline chart. These are outstanding at showing variances:
The chart above shows two measures which are showing the upper and lower values. in my use case I could then have the MRRP versus whats its being sold at:
I.e. MRRP is £10 but is being sold for £12, on that day we could then see a £2 spline indicating how much the price is off the reccommended.
So many use cases for this flexible chart.