First things first. Apologies. If I offend people with what I post or scare people away from posting, i'm deeply sorry. I have never been the best communicator, and I tend to get rather emotive with my responses because I care, instead of logically explaining my arguments which would be much better. I have been keeping myself away from here because I always end up doing a bad job of expressing what I want to convey and inadvertently upset or put people off.
Working in IT my response was an emotive response in this thread and didn't really explain anything.
1) The Switch review.
Most Network standards are defined by the "Institue of Electrical and Electronic Engineers". These make their way down into Regional Standards as highlighted in the link i sent previously. "TIA" (Telecommunications Industry Association) for America, "CENELEC" (European Committee for Electrotechnical Standardisation) for Europe and "ISO" (International Organisation for Standardization) for the rest of the world. Although these exist as guidelines, these guidelines can often also be enshrined in law. As switch communication has to use the same protocols and standards to talk to each other, the minimum standards of hardware also has to comply by is also the same, whether the device sits in a datacentre that requires you to wear ear defenders to enter, or in your own home.
The way all switches communicate with each other and networks handle data is also important. Rather than me try to explain badly why this is relevant, see the below:
View: https://www.youtube.com/watch?v=t-ai8JzhHuY
Understanding the basic concept now of how computers talk to each other see the below on the two main protocols TCP & UDP
View: https://www.youtube.com/watch?v=cA9ZJdqzOoU
Most Audio Visual applications these days (unless it's a live stream though more and more of these now are buffered TCP streams) will use TCP over UDP. Using TCP, it's technically impossible to lose the original data source or for it to be different at the destination.
What If their is any EM induced harmonics or noise generated that interferes with a transmission? The device stops working (the classic example is your router next to christmas lights) or it degrades it's throughput. This would be rather disasterous for a UDP live stream, but would reduce throughput on a TCP stream but the original data would be intact unless the signal is drowned out. This is not something an AV switch would fix. If their is a bad cable or SFP failure. then what? Errors are generated on switch port interfaces which will remove a link or a switch if necessary from service, re-route traffic and send out alerts to Technicians and administrators for them to fix a fault in the datacentre/ISP world. For us at home, we would just replace the cable.
For an AV switch to therefore be magnitudes better than a convential switch should not be possible as they all use the same standards. Unless such a manufacturer can produce data metrics in a replicatable test environment to prove otherwise, please please please don't be foold and save yourselves the money, but ultimately it's up to you.
2) Cabling
Again Ethernet cabling is again based on standards defined by the IEEE. As laid out in the link I posted previously, CAT7 cabling is designed for a use case in datacentres handling huge quantities of data that far exceeds the requirements of a typical home user. If their is a cost difference, most people at home should not need to go higher than CAT 6 or CAT6A based on bandwitdth and throughput.
The bit that will be of more interest to the AV community is the different types of the same category of cable, and depending on the location of your kit will benefit from a U/FTP (Unshielded Foiled Twisted Pair) or S/FTP (Shielded Foiled Twisted Pair) over standard UTP (Unshielded Twisted Pair) cabling as it adds layers of protection to cabling to protect it against EM and Harmonic Interference).
Do I believe that Ethernet Cabling makes a difference? Category wise, CAT 6 or 6A is the sweet spot, any higher typically is a considerable cost jump and not justifiabe based on my home use case. I do purchase U/FTP or S/FTP cables from a reputable cabing manufacturer such as Excel, but not Audio Visual Cabling, because their are no percievable benefits from doing so for a significant jump in £s.
Have I purchase and Do I believe their is a place for AV cabling manufacturers? Yes. Through my own experiences I have found that conventional USB cables (even when swapped) were creating Jitter to my DAC), and Also more recently I have also changed my basic XLR cables which corrected a long standing issue with channel imbalance between my DAC and AMP and totally transformed the sound. Would I spend £100s or £1000s. no.
Again, these are my opinions. Make of them what you will. I hope i've done a better job of trying to explain myself this time...