The OEM roof isn't actually fabric, it's some weird Japanese vinyl so although these kits work I went a different route. Mine was full of mould, that horrible green stuff so I gave it a couple of warm washes with Hibiscrub, the stuff they 'scrub-up' with before they operate, I repeat this every spring and that has totally cured the mould problem. For reproofing I have used Scotchguard-like products in the past but recently found http://www.amazon.co.uk/gp/product/B0035FAYKS?psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00 this stuff which works a treat, although there's a product called 303 which also works well. I have also found that for my regular cleaning this stuff http://www.amazon.co.uk/gp/product/B001RE3FLO/ref=pd_sim_200_4?ie=UTF8&refRID=1JQ4PYHN6ZTH0WXV0XZW&dpID=51q79x4B1aL&dpSrc=sims&preST=_AC_UL160_SR132%2C160_ which also does what it says on the tin/plastic bottle!
As for blackening, the Scotchguard gives it a kind of lighter shine which I think looks OK on my Gunmetal car, while the 303 Aerospace stuff makes it black and shiny.