This is finally done. You can now compare with both dimension values and time ranges as your dimension down the left side, including the ability to align trend lines for comparison periods on the same graph. 

@Simon_Pilkowski: Noted, it's still something we are actively pursuing! 

@Andreas_B: Good catch. I will check with our engineering team to see if this is something we can easily add. 

@AndyW: Good idea! Thanks for submitting. 

@Stef: I believe this is still only in Ad Hoc Analysis. We are looking at adding it to Analysis Workspace, specifically for the Flow visualization. Other than that, I don't believe this is among hte many features we are currently working on. 

@JoyWend1: Thanks for the suggestion! 

@Alyson_Murphy Noted. Thanks! 

@ProletM Great use case. Thanks! 

@Alyson_Murphy: Hooray for placation!  

@jonathan_roy: Good request! Thank you for submitting. We will keep an eye on it.