I don't know about Shunyata vs Puritan directly. I have had 2 clients compare a Torus directly with Puritan and both kept the Torus. I have other clients with Shunyata Everest that don't plug their amps into the Everest. But they do plug them into a Torus.
My perception now is pretty much everyone will benefit from a filter. But you have to apply them correctly. A filter will find front end gear more forgiving. As in, more filters are apt to create a pleasant sonic change on signal equipment. Amps are more difficult. I have heard a couple people say they can get an amp on a Everest. I have heard others that say the background gets more quiet but the dynamics and soundstage suffer. I have had 3 people tell me they hear the Puritan compress the amp if they run 2 on 1 Puritan. One is a Puritan dealer and uses my Torus now. Puritan might work on a smaller stereo amp. But the second amp collapses the soundstage.
Almost universally a Torus on amps will result in a more quiet background, greater dynamics, an expanded soundstage and a sense instruments are more real. I personally have never heard it go other than that. I say almost universally as someone is bound to say they heard something else. But then I question whether it was installed correctly.
All filters have to be powered correctly The idea that a filter fixes poor inwall wiring is a myth and untrue. A filter will always perform at a higher level if you feed it a dedicated circuit. They will all suffer if the wire feeding it is insufficient. Filters are only their to remove noise. Generally high frequency. Low order harmonics as in 11th/12th and lower seem to walk right through every filter I have ever put a scope on. Whats more, the back pollution from filters like Shunyata, AQ and Puritan onto the main is massive. I did a live measure of a branch wire with 2 x Everest on it. You could actively watch the THD through my scooe jump to 17% as soon as they were plugged into the wall. I had a Furman sending so much back polution the circuit breaker in the panel was audibly buzzing in the room with the cover closed. We unplugged the Furman and the buzz was eliminated.
Puritan is a good budget filter. But I would argue a $3999 Torus RM20 is far more versatile and gives better overall sonic performanc.
FWIW I have put 2 x ARC Ref 160 and 2 x REL T32 on a single RM20. It was easy to hear it was better on all levels. That is way overloading that unit. But the point is that even that overloaded it improved and did not hinder the playack.