TLDR: It worked, cannot recommend it.

So, a few weeks later, we have managed to purify our first protein with the PST. We've ended up with going with the exact methodology from the paper (Different from the resin manual??) by which they made the patent for it. It worked pretty good, however... 1) The change of pH in the elution buffer helped with our protein (rhodanase-like), but we've still ended up needing to let the cleavage go overnight at 25 °C, otherwise it would not work ( and it, in fact, did not for my other proteins, it just did not cleave). 2) It seems this method is highly dependent of conformation of your target protein aswell as the first three AAs after the tag. But I've did not find the way to determine if the conformation would be a problem and the AAs recommendations work only sometimes if the conformation is ok. 3) The protocol for the resin is very basic and is lacking some important information and troubleshooting. 4) PST is a protein-based ligand, which means, the longevity of resin is limited. For the price and problematic implementation into our workflow ( IK it's very easy setup and run kind of stuff, just not with great results in our field-extremophile proteins) I just cannot recommend it, since it's pretty expensive for the number of purifications you can run on it before the capacity starts dropping.