In our product we have different tenants of the product sitting on top of a single site (ecommerce application aimed at different markets and each market/product type has it's owne url). I have set up transactions against each of the tenants and it would be beneficial to compare the performance between different transactions. So the use case is:
As a user I want to be able to compare 2 or more different detailed visualisations using the same time period and scale on the Y axis (for the performace). This way I can see if performance trends are similar on the different sites easily.