@JaysynSlayde I’m calling it “Boom Chuck with Upstrokes” because it encompasses more than just “Boom Chuck-a” – there’s also “Boom Chuck Boom a-Chuck-a”, “Boom Chuck-a Boom-a-Chuck-a”, etc., and I want to allow for the ability to have the strum change from measure to measure for variety. And of course, Tony Rice had a lot of super-tasty variation and syncopation in his strumming, which I’m unlikely to be able to emulate with code – it’s hard enough to emulate as a human!
Anyway, as a trad-bluegrass banjo player myself I know exactly what you mean and I will definitely be including this kind of rhythm in the new update. 
Most likely you’ll be able to say "just play “boom chuck-a over and over” if you want that, although it will default to a more nuanced strum like the pros use.