I prefer Gwyneth, mainly because it seems lighter and more current to me, Gwenith seems dated like Glynis. I could warm up to Gwenyth, but not Gwenith so much. And because Gwyneth seems more authentic. I wouldn't hesitate to nickname a Gwyneth "Gwen."
thank you. Gwyneth nn Gwen has pretty much been my plan all along I just didn't know if that seemed weird to people who pronounce Gwyn and Gwen differently. I just like the look of Gwen a thousand time better than Gwyn