Re: back pressure - that's what I was most interested in, and I was sad to see it not addressed. I got a silent brass mute for my horn (trombone) a couple of years ago, but found that playing with the mute in (like any other practice mute that I have used) felt extremely different than playing without; especially in lower registers. Even the older version was magical - making me silent but still able to hear myself, but the cost is long term usability.
I'm a string player. You can get practice mutes for string instruments, and somewhat analogous to back pressure, they change how the instrument responds to the bow. The result is that you can practice some things (left hand technique, repertoire) but not others.
For myself, I'm practicing for pleasure and not to advance professionally. Muting my instrument would spoil it. Fortunately I've got a tolerant family and a detached house.
Sadly, that article is a few years out of date. Still, my big takeaway was that I would be willing to forego some attenuation and even cope with modest back pressure if the mute didn't mess with the tuning properties.
I've been pretty happy with the soft tone mute. It's pretty quiet (but louder than most), is better than many practice mutes for back pressure, and seems to have little impact on tuning. For reference, I'm playing a King 3b, no f attachment.
Maybe if I start spending more time with my horn again, I'll consider the silent brass as it seems pretty sweet for recording.
