Not sure what to say about this. I don't talk about it much with strangers. My friends and family seemed to think that donating a kidney was a bigger deal than giving away or foregoing a lot of income; I don't really agree. Broadly, I think that donating a kidney has convinced people I have more "skin in the game" than just working for GiveWell has, and I can think of one or two cases where this has made them more likely to take my advice on charitable donations. I think that if I were more comfortable talking about organ donation, it would be possible to use that as an entree into talking about charity: "... but you don't have to donate a kidney to make a huge difference! Just donating money can also be transformative."

On the other hand, I think it's at least possible that the net effect could be harmful. Kidney donation is still widely perceived (incorrectly, I've argued) as a big deal, so if you're trying to convince people that donating a portion of their income is easy, it could be a disadvantage.