It's probably bad form to quote oneself, but anyway ...I find I need to turn up the lows when switching from the arco to the pizz setting. This with the original NS strings - perhaps proper strings have more lows in the pizz setting?
Your observation is correct for the other strings I am using too. I know this because I spent the first 20 minutes of a set on Saturday puzzling over my tone, wondering where all the low end had gone. Turns out I must have accidentally flipped the aroc/pizz switch to pizz sometime during the break. I was worried I had blown the speaker or something.
Jennifer