Hi AJ/Don
I've just started using the SD40 and the Fishman Triple Play, I've found that with the pianist set to auto the SD40 recognises three string chords and allows you to solo using one or two strings, if you set the pianist to standard then the chord changes every time you play a single string. The auto setting also works very well without using a sustain pedal.
Hope this helps, I'm really enjoying the SD40 and my guitar playing is improving day by day.
PS: The string sensitivity on the Triple Play needs adjusting to suite your style of playing, this is a simple operation using the Triple Play software.
Kind Regards, Col