I have one VXDIAG Subaru SSM3 and find it useful as it will talk to everything on the car, including immobilizer systems. . . it emulates the SSM3 and uses cracked SSM software and its own VXDIAG driver (which is why it’s such a pain to set up). It is *extremely* picky about operating system. I wound up having to buy a new(ish) laptop running win7 to get it going.
But my mission is a bit different from most. I make and program keys for a living and for a while the SSM was the only thing that would program the prox fobs. Not true anymore but I still paid less for the VXdiag with software than I would for a single piece of software for my T-code pro. . and there are 3 for Subaru. I have one which only covers the earliest models.
I also find it handy for doing stuff like turning off the passenger seat belt warning (my dog rides over there sometimes and doesn’t like wearing his belt) or setting the wiper de-icer to work for as long as I tell it to instead of a 12 minute cycle. Or make the door locks unlock with one press of the remote. All of this is stuff you won’t be able to do (AFAIK) with any other scanner.
I also rebuild wrecks and it’s the only thing that will talk to the airbag systems so I can figure out WTF is making the light stay on after cobbling together a car from 2 or 3 others.
You could pay the $3k for a legit SSM3 plus another $2k/year for software and have no problems with install. . .
But if all you want to do is check/clear codes and view live engine data occasionally, yeah, you don’t need OEM one. Just go for a clone.
You need an immobilizer code (which is VIN specific) to program keys/fobs. It does not change so once you have it for your car you can go nuts. Odds are your dealer would probably give you your immobilizer code if you shop there somewhat regularly. They may charge you for it as I know they have to pay a couple of bucks to mama subie for them.
There’s also an ‘enabling password’ which is also static and I suppose is a very flimsy extra layer of security to protect the immobilizer features of the SSM. It’s 3781.
P.s. If you feel pain to set up software, the video will help you out. it’s about Subaru SSM III software installation.