Good lord, are we still obsessing over toilet paper?
For the swirl test to be even remotely valid, you have to take a wad of poop paper, prepare it in whatever configuration you normally use, wipe it across yourself, collecting as much detritus as possible, then with at least half a dozen witnesses present, drop it in a clear jar, cap it off and give it a swirl.
Only then will you truly know how it behaves in the holding tank. As long as what you are sending down there isn't bigger than the opening at the termination valve, it will sit in the holding tank, percolate real nice, and then flow out when you dump the tanks.