update.
Tried the CarPro DLUX a couple of weeks ago and it worked perfectly. It produces a very black satin sheen to the rubber and has completely masked the matt/faded and blotchy rubber trim around the windows. it now looks black permanently and appears like its just been treated every time I approach the car.
The instructions are very basic: apply, leave for 10mins, wipe off. No indication of whether it can be done in direct sun light or not, either way it worked fine in both conditions as it was patchy sunshine and cloud all day. After reading about applying it on another forum, some people buff straight away some leave for a little time. I tried both methods and think they work equally well as long as you don't apply to much. If you do simply distribute as you buff, but do it straight away.
To give you an idea of usage, I only have the rear lower exhaust trim panel to do with 1/2 of the bottle remaining this probably indicates I applied too much in general, but as its designed to last a year or more I don't mind the expense.
I tend to look after my cars in general so with the car garaged and only 11k miles after 2 years, its not like its been sitting out in all weathers, but the trim has now been made to look better than new..