This is a great idea, but it’s also problematic.
What’s happening is that you are cloning that circle. The cloned circle then lives with the users but no longer receives the benefit of updates to the original. Perhaps a more symbiotic relationship would be beneficial. For instance, let’s say I share my Beer circle with you. Let’s say I make updates to my beer circle, it would be great if your new Beer circle was linked to mine and you’d have the option of adding people I’ve added (or subtracting subtracted).
The Scoble Effect. I’m really grateful that Robert Scoble put me in one of his shared circles. I had to turn off notifications on my phone for now because since he shared the circle, I have 2500 new followers and counting. I am not complaining, I’m just demonstrating to power of Scoble.