I've been playing with the acrylic amide polymer I use at my slaving dayjob. It's very similar to this Eudradgit crap(I hope I spelled the gak name right) that is added to pills. In water solution, Ferric chloride makes it just coagulate into little pieces. The volume of brown precipitated crap I mentioned earlier was using an amount of this polymer which is well beyond that found in pills. Seems that this general method works on that shit too. I'll have to try this on those new gas station ephedrine pills in a water extraction to see if it tames that swelling...free base sucking...won't extract crap...I saw using a waterless a/b. I tested the water left over from the ferric chloride whacking. I added enough plus about 20% to leave a yellow colored water after the polymer fell out. The remaining water had none of it's previous properties, which was to coagulate metal particles in water.
As to the greater gak resistance of the LWR method, if I had been forced to guess I would have said that they would be about equal since they both work by the same mechanism. Maybe the greater concentration of ingredients of the push pull is what makes it puke out first.
I've never tried a push pull because since I raise a couple of kids now, I have to make my felonies count. I thought there was little I could add to that area, and I would only consider sticking my neck out for novel methods with possible clandestine application, and of course checking out new pill formulations.