I would like a “Change quantity” link added to the user/uid/subscription page. This page would allow the user to adjust quantities of a plan up or down.
The module should be aware of the settings configuration>Web Services>Recurly> for “Upgrade plan behavior” and “Downgrade plan behavior”.
I think there might need to be some logic to hide or show both the “change plan” link as well as the “change quantity” link on the list page. When in multiple-plan mode, you don’t really need a “change plan” option, although I suppose it doesn't really hurt. But not everyone will want a “change quantity” option.