Paul I. wrote:
 Good stuff, but you need to go with light colors to keep the temp down. BUT, the light colors show the dirt more & it will stain. I got some silicone sealent and oil on it and the rings will not come off. For the price, its hard to beat!
Well, silicone would be a problem for just about any surface, bummer you got stuck with the stain.  As for regular dirt, the flexiteek (and others, presumably) do a much better job of hiding the dirt than bare non-skid would.  When our boat gets a bit dirty from just ambient pollution (like any nearby diesel boats) the gelcoat areas show up a lot nicer after cleaning.  The teak stuff doesn't really look much different.  So it'd have to be really filthy to start showing much.  I don't think they offer variations (or didn't when this was new).  In bright sun it really does show up as a nice lighter tan color.  Cloudy days make it look a bit grayish.
I've heard fake teak products with a white seam are a little "less worse" than the same product with black seams, heat-wise.  But then you're back to dealing with the appearance of dirt.