I was wondering what impact on sound and playing drilled guitar picks have. I have tried one and did not notice any kind of difference with regular flat picks. Is it supposed to make for a better grip ? or a different flexibility curve ? Maybe it is just a convenient thing for for tying them on a necklace or a key chain ?
No difference! The hole is, yes, really to give a better grip. I am certain, even if you had Clapton's (for example) guitar, set up like it was, straight after his gig, and used his pick, you still wouldn't sound like him! The pick is only a bit of plastic, but there are a myriad of different ways to wield it, and we each have our own way(s). Make nice earrings too...One of my students used to wear them.