Convenience vs Functionality, I'd hardly say the bare betal teensy is a "better deal" to someone who ONLY wants the capabilities of the Ducky, the ducky comes in a nicer case and has a whole scripting language built around the endgoal, emulating an HID. However if you want to use the teensy and have the know how to program it then fashion a case for it (even if that IS easy as fuck) then yeah get the teensy, it's jsut a matter of what your time is worth and what features you want.