No, it hasn't. I was quite shocked when I looked at some pH tested levels, to see that Kon-Peki was over 9. That is the same as BSB, but to my knowledge, no-one has experienced the staining associated with BSB with KP.
I have a feeling it isn't all about the pH level...
Edit - pH levels post http://www.fountainp...-of-inks/page-3
Wow. Baystate Blue is very basic. It is on the same level as baking soda on the pH scale!