I'm riding a 53cm frame on the Silhouette. PBS is taking a look at it today and to their credit they're giving it a more detailed exam (without my asking) due to the malfunction on each ride. Sad thing though, the paint got really scratched up when the chain dropped.
Will wait to see how it turns out. A mechanic at one of the LBS told me that a lot of the manufacturers are now installing triple shifters on standard double rings, due to efficiency in installation. The manufacturers do list a warning of "overshifting" due to the difference. Hope I got his explanation correct.