I am using the Gath Gedi w/ Full Visor. It has been great, esp when launching and I have the foil upside down and the wing tips are banging me on the head and potentially in my eye, the full visor saves me on a regular basis. It comes stock with a shorter visor and the full can be added as an option.
WRT fit, yes, you need to get it to fit snug, but not too tight, so I used some extra helmet padding I had w/ some contact cement to customize my fit.
The visor does blur your view a bit, but I really like getting the sun exposure off my already sun damaged face.