I understand, the reason why I mentioned it was because I completely agreed with you to the impressions of the extreme - pro. The holography is something you mentioned, and the Micron not only bring in the holography but also the details, dynamic, it is the combination of both the Swiss and the Extreme Pro. (From similar views of the extreme pro in references to the Swiss)
The bass will be different, and if one love the Sandisk Bass and mid, the Edge is the best fit. The Micron is more neutral than the Edge which is more musical.
The one reason why I recommend the Micron to many people is because for the dollars per Gb spent, the Micron is of the best value. But honestly, the Edge is very preferred , unfortunately it cost as much as 1Tb Micron for only 400Gb
I have really scoured through tons of datasheets, website whitepapers and various other scientific papers on Microsd manufacturing, technology and implementations of the various manufacturers.
There's also other brands that produces Industrial Microsd that I have considered like Apacer, Greenliant, Flexxon.
The choice for Swissbit came down to it's website which has very detailed information about their quality controls and testing:
https://www.swissbit.com/en/blog/post/the-secret-of-swissbit-product-quality-part-i/
https://www.swissbit.com/en/blog/post/the-secret-of-swissbit-product-quality-part-ii/
This is the price difference:
In USD$
Sandisk Industrial IX QD342 256GB 3D TLC(?) $262.78
Apacer CV110-MSD 256GB 3D TLC $219.92
Sandisk Edge 256GB 3D TLC(?) $210.07 (out of stock, 20 weeks wait)
Swissbit S-55u (Industrial model, not Extended) 256GB 3D TLC: $151.15
Micron I300 256GB QLC $113.01
GreenLiant 256GB QLC $85.29
So you can see, the Swissbit is actually the lowest costing 3D TLC on the mouser site.
I would likely try out the Micron I300 in the future.
Just to share my insight into the Industrial Microsd cards after doing so much research into them:
These Industrial cards are used in the medical, military and financial sectors, so they must be able to store and retrieve data with extreme reliability and as well as able to operate in the harshest condition like in desert or inside automotive vehicle engine bay area or inside a search and rescue drone flying in the winter.
Conformal Coating which resist corrosion and humidity (though some consumer professional cards have them too)
Wider working temperatures (right down to -40 degrees Celsius)
EMI and Vibration tested
Better data protection against sudden Power failure
More powerful Error Correction Engine, normal consumer grade cards usually uses BCH error correction, more advanced industrial cards uses LDPC (like Micron)
Better Wear Leveling implementation which means the card can last longer for intensive writes
Software Health Monitoring Tool (some brands)
More thicker Gold coating for pinouts, exceeding the standard SDA spec of 10,000 insertions. Some cards like Swissbit is spec to 20,000 Insertions.
So how does all these affect the sound quality of the walkman? To be honest, I don't know exactly. Your guess is as good as mine.