My first experience was promising.
The car, a 4 year Honda Civic Tourer with 30 thousand km on the clock, was dirty from the first road salt on the roads this "winter" (came from up north to visit us in the "south") but no sand etc. on the paint. I did only pre-spray (didn't really soak them) the lower panels. The sponge feels more like of a groute sponge than a traditional car wash sponge, or a mixture of those? I started with the roof, and without pre-spray, and it felt weirdly ok and because this car was not a neglected car, no sound of friction could be heard. Felt good, in fact! The car has been used in automatic car washes so swirls can be seen. The car has minimal roof bars and the sponge handled them really well. Always turned the sponge and went one more time over ever panel. Did not catch all dirt because the drying towels (The rag company Minx) did get a bit dirty (not on the roof section but when washing windows where there is parts where dirt can hide, window trims are pure evil!). I'm used to use a CG Big Chubby microfiber sponge but I think I have never tried to wash a car this dirty without rinsing it off so I can't compare them yet. I was *very* gentle with the sponge, didn't use any force. The sponge did get a bit of beating when washing parts that had a hard edge like the register plate etc. so one have to be aware of that aspect, it is still a sponge. I still think this could be the best rinseless wash media (after using a lot of towels or pre-rinsing) if you want to wash a quite dirty car without rinsing it off before a wash! Next wash I will start with pre-sparying every panel as I go through them, one by one (all steps, also drying).
The bad thing is that the Big Red Spong costs 35€ from where I ordered one (http://optimumcarcare.nl) and now they out of stock. My order was first to be cancelled because they did not have any BRS in their inventory but then they eventually found one for me. Did order other Optimum products at the same time and the price was on par with what I get in my own country, and we don't even have Opti-Clean available, so then I could justify the high price of the BRS, at least in a way.
Still to be continued....