I really like the idea of the Sun visor, but I like riding with my shield up most of the time. I am thinking that this would be a bad combination?
If you are referring to the
Super-Visor (pictured below), I have found that with the face-shield (clear shield) up, there is a bit more wind resistance generated by the visor sticking into the windstream. This is not really noticable or problematic at city speeds, but can be a bit of a nuisance at highway speeds. It pulls your head back.
Having said that, I usually put the clear shield (to which the Super-Visor is attached) down for highway riding, that moots the problem. I have not noticed any increase in wind resistance when riding at high speed (up to 200 km/h steady speeds in Germany) with the visor attached and the clear shield down.
It is possible to remove the visor from the helmet, because it is attached with industrial-spec Velcro strips. But, I don't think that it was designed for constant removal & replacement, my guess is that the adhesive side of the Velcro would start to peel from the visor or the face-shield if it was removed more than 50 or 100 times.
I've had mine for over 10 years, I am very satisfied with it. For $20, you can't go too far wrong.
Michael
'Super-Visor' helmet visor