I will buy your cartridge should it have a 9.2.0 update on it.
As for why nobody else has that firmware, it's because this is the first time this is a cartridge-based update. Cartridge-based updates don't update the online browser stuff, so the part after the dash won't change. Your system currently has -17, so will remain -17. Over-the-Internet updates, however, will update the online components, and everyone who currently has 9.2.0 either had it installed at the factory or downloaded it from the Internet, so have -20.
As for why nobody else has that firmware, it's because this is the first time this is a cartridge-based update. Cartridge-based updates don't update the online browser stuff, so the part after the dash won't change. Your system currently has -17, so will remain -17. Over-the-Internet updates, however, will update the online components, and everyone who currently has 9.2.0 either had it installed at the factory or downloaded it from the Internet, so have -20.