Between the two speakers, I would describe the Sierra-1 as being more musical, smoother sounding and more refined but yet capable of resolving more detail. The Sierra-1 is also considerably more transparent sounding combined with superior imaging – thanks to its extremely inert cabinetry and higher end components.
The 340 is capable of playing louder and will demand less power from your receiver. It is also a music lover’s loudspeaker but is not capable of the disappearing act or refinement presented by the Sierra-1.
Bang for buck, the 340 is nearly impossible to beat and is an overall very well rounded loudspeaker. If you want serious emotional involvement with your music listening, the Sierra-1 is the better choice.