Given that I've written much of the documentation for RSS Bandit on the documentation site and have spent a lot of time in the code making a few contributions here and there, I feel a bit sheepish that I didn't know about this particular feature.
After reading this post (which is one of many discussing how to create one click subscription links) from Phil Ringnalda I discovered that a common way to subscribe to an RSS (or ATOM) feed is to merely drag the link into your aggregator.
I hadn't seen that described before so I thought I'd try it out with RSS Bandit and sure enough it works. Sweet! I'll have to add that to the docs.