I bought one. Don't know if it works - but sits in the glove box giving me the peace of mind that I will have done all I could if the problem ever comes up.
When I bought it it was cheaper if it only was used on one VIN. They wanted more for a unit that would work on any VIN. Otherwise I would have happily loaned it out (with a deposit) just to find out if it worked for anyone. Maybe a group buy for interested parties?
The VIN encoding is the kicker for reverse engineering. I could see spoofing a failure in my own van to attempt to capture the codes, but am very reluctant to go down that road. And the VIN encoding prevents sending it to someone who has an actual failure. I just figure it will either work or it won't.
The other trick to keep in mind is Dennis's trick of pulling a NOX sensor (I believe it was a NOX sensor?) leaving the hole open and confusing the system to the point that it takes no action on the countdown.