Is a shiny roof a good thing?

Is a glossy boat roof a bad thing because of the sun's reflections dazzling the helmsman?  I'd be glad if anyone can enlighten me.  

We've always gone for a matt or satin surface, mostly raddle, but I have a suspicion that it might not be so hard wearing and is more susceptible to grime.  I do notice that when we wash Herbie's roof that the run off water takes on some of the raddle colour. I don't know, but I imagine a gloss surface might not do that so much.

The gentleman a few boats across from Herbie has just repainted his roof with International Toplac Plus which is a more modern formulation with the advantage that you can just roller it on withouth having to lay it off with a brush.  He certainly made short work of it and got a good finish with just a foam roller.  It does however produce a gloss finish.

I know some hire fleets use gloss paint on their roofs, Wyvern and Heyford spring to mind.  These folks would go for hard wearing I suppose.

If anyone can venture an informed opinion, I'm all ears.

It would take a great deal of persuasion for me to change from Craftmaster paints on the cabin sides, which are of course gloss. It's such lovely stuff to paint with and goes on easier and covers better than anything else I have tried.  However, I have a problem because they no longer offer the Light Grey colour we previously used, and I don't have sufficient left of the old paint to complete the job. I suspect they might have abandoned that shade because it did change colour after a while, presumambly from the action of UV light.  Our old Light Grey has taken on a distinctly blue hue.  

I some lights it can look extraordinarily blue like here:

That was at our lovely mooring spot at Ventnor marina, which wasn't so lovely in that that flippin' weeping willow tree draped wet leaves all over the roof in winter and played havoc with the paintwork.  Which brings me back to my earlier question. Would a hard gloss finish survive that sort of thing better?