Voice inversion is still used, but it's rare.
In Northern California the State Department of Justice (DOJ) uses voice inversion and I've found one (small) law enforcement agency that uses it on occasion.
I've also heard a couple taxi cab companies using the inversion.
I've got the card for my 8200, and it works very well.
The only two setbacks about the card is;
1. It doesn't detect the setting ( IE it doesnt scan the voice inversion variables )
2. It's either on/off. It doesn't activate by itself. If you come across an inverted signal, then you must "turn on" your card.
I've also come across some voice inversion programs online.
Inversion is used a lot in the Cleveland area. There are 3 departments in the area that use it frequently. One county agency that uses it all the time. And two agencies that use it on their Tac frequencies. I have no experience with the VI8200 so I am unsure how well it works.