Just to update, after a couple of hours playing with it, I am finally noticing it fluxuates up and down. It appears to let go of consumed memory after a period of inactivity. That's great news!
Glad to hear it! But as implied above, memory consumption is only interesting because of its effects on performance and stability (both of the browser and other programs running on the system). Don't choose your browser by looking at the memory consumption, choose your browser based on how it feels when you use it.
So far in my testing and browsing, it is.