I've not used AG soft top products and I've never gone down the Fabsil route. Only Renovo
The Midget that I owned for years was a vinyl roof, which of all things I used Dubbin on, mostly in an attempt to waterproof the stitching. How it has survived this far is astonishing because on reflection I would have thought Dubbin might have rotted the vinyl by now!
I did my own research when I acquired my convertible SAAB and my cleaning routine would literally take an entire weekend and was exhausting when done properly - but boy, did the car go lots better after!
I would always clean the roof on a separate day to the rest of the car - this was due to the use of snow-foam and the drifting mist from the pressure washer getting the roof wet, however its a bit of a dilemma which to do first because Renovo can stain the paint a bit (not permanently) but its a bit of a pain to remove. But then I didn't want snow-foam drifting onto my pristine clean roof!
As we are talking just hood this is what my routine was...
Using a medium clothes brush, thoroughly brush the dust off the hood.
Using a stiff nylon nail brush I would open up the gutter and get all the build up of dirt and dust out from the fold. You will be amazed how quickly that gets fouled up. Don't go too crazy because there is a slight risk that you are going to wear the stitching.
Follow this up with a good vacuuming and maybe vacuum in conjunction with brushing. Try and remove any green lichen that might be setting in.
Following Renovo's instructions use Renovo canvas cleaner (A point to note here; MAKE DOUBLY SURE YOU ARE USING RENOVO PRODUCTS FOR CANVAS AND
NOT FOR VINYL - the bottles look similar!)
I had a jug and paint brushes marked solely for use with each of these products and nothing else.
Brushing the Renovo on to a dry hood is a bit of a pain because it has a tendency to run off down the glass and paint. I think this isn't too much of a problem - its the Ultra Proofer that tends to stain the paint. (Sometimes, if I was not just doing a quick 'interim' job, I would mask up the car with huge sheets of brown greaseproof paper using blue low-tack masking tape easily available from any auto-paint supplier or fleabay). Using a decent paintbrush (4") - work the product into the warp and weft of the fabric. It's hard work but its worth it.
Once the hood was properly cleaned and fully dry, brush and vacuum it again, then use the Renovo Ultra Proofer in the same manner with a separate brush just for that product.
If the hood is starting to look a little faded there is another Renovo product called 'Soft top Reviver' - assuming your hood is black, buy the black version. Although I had a huge bottle of that I never got around to using it but a fellow down the road used some on his BMW and it did a very good job as far as I could see, but his BMW was old and the roof looked really tired.
I never felt my SAAB had got to that stage.
Feel free to ask more questions if you need further info