As far as I can tell Goop is merely filter media rinsed or sqeezed out into a new tank. Add enough and it will be an instant cycle, With the proper bottled bacteria there is a slight delay. The bacteria in the bottle are in a state of cdormancy when you pout them into a tank. The prresence of ammonia wakes them up and they get right to work. But the is a bit of a delay between when your pour them into the tank with ammonia and when they are actually working at full strength.
With filter medie additions you are adding liave active bacteria that does not need to wake up.
There are two main differences between added Dr. Tim's for example and adding filter squeezings. First, the bottle bacteria is specific about the tank size it is good for. However, we have no idea how much bacteria we may be adding with filter squeezing and I am not sure how accurate Goop is no matter what they claim. My guess is they just use more than is needed to be sure it works as advertise on a given size tank.
Next, am maybe more importantly, bottled bacteria contains no nasties. if is grown in a nasty-free environment and goes into the bottle with mor germs or parasites. Fitler squeezings will certainly contain bacteria and likely parasites as well in lower levels. Most healthy fish can fight off such minimal numbers with the natural immunity. Stressed or weak fish cannot do this. The risk is even greater when the squeezings come from someone eles's tank.
I have read their site information and they do not do two things. The first is they do not tell you how they culture the bacteria, The second is they do not identify the specific strains of bacteria in the bottle. If they are basically culturing in an established aquarium with fish etc, of of they use squeezings a s astarter from wich they culture the bacteria, they are likely violating a patent on the Nitrorpira in their product. And established tank, in fresh, brackish or salt water will have Nitrospira.
I have seeded tanks and my bio-farm both ways- using dr. Tim's and or filter squeezings. Both work. But I am cheap about it. When I use the One and Only I buy about 1/2 or less of what I actually should and then cuclture the rest myself in the biofarm by adding ammonia until I have what I need fully ready.