I don't like the Gary Dean method of washing the vehicle using ONR for a few reasons:
When you are done washing your vehicle you have to wash what could be a large stack of microfiber wash cloths in the washing machine. If one of your objectives with using a rinse less car wash is to conserve water this method requires lots of water before all is done.
Microfiber wash cloths and microfiber towels are great for washing windows, drying off the vehicle. One major annoyance with the micro fiber cloths is that they effectively trap organic debris such as seeds, plant burs, etc. Removing this organic debris from the microfiber cloth after cold water washing and air only (no heat please) drying is a tedious job. I can only imagine if I had to remove organic crap from a couple of dozen microfiber wash cloths.
The cross cut sponges such as the Big Red Sponge can be easily rinsed clean when done, do not accumulate the organic particles to nearly the same degree as the microfiber cloths.
Well, to be clear...I only wash the microfiber towels when I have enough to wash. Usually....after doing 2-3 cars (so there are like 12-15 microfiber towels and 3 drying towels to wash). If I just do 1 car, I'll do a quick rinse to get most the dirt off the towels and let them dry...and put them in a "dirty towels" drawer and wash them in a machine later.
And....the water conversation difference is minimal, at best, vs a sponge ONR system vs gary dean method? First.....yes, both systems save a lot of water vs a hose/pressure washer, hose rinse type of car cleaning. But comparing the two....I'm using, maybe 1/2 gallon of water to wet the 4-6 microfiber towels. Lets say I wash my towels when I've done....2 cars. My front load, HE washing machine uses 7 gallons of water when doing a wash. So for 1 car....that is: 1/2 gallon to wash the car, 3.5gallons to wash the towels. So 4 gallons. Of course, even less if I wait until its 3 cars worth of towels. VS.....sponge ONR method? You probably use 4 gallons when filling up a 5 gallon rinse bucket? And....you'll have to eventually do a load of laundry anyway...since you shouldn't reuse drying towels (drying towels accumulate any leftover dirt that is on the surface of the car). So...yeah, difference is going to be minimal.
Comparing gary dean vs sponge method....is for ease of use. Dunking a sponge in rinse water would suck in the winter, even in a garage. Plus it takes longer than just flipping to a new side of a towel. Plus I don't have to wait to fill it, or lug the 4 gallons around, etc.
The "organic debris" problem you are having....I definitely don't have, so sounds anecdotal. Maybe because I park cars inside instead of under a tree? Never had an issue with seeds.....only thing on the car is road dirt/bugs. Both come out 99% after the washing machine. Again, just anecdotally, but I've heard the opposite problem with sponges on the detailing forums. That sponges trap hard debris (like a seed) and don't release them when washed vs microfiber, thus sponges have a higher likelihood of microscratches vs towels. (or just, in general, using a rinse bucket doesn't fully release the dirt into the bucket so its safer to use "always clean" side of a microfiber.)