It was a model that sold in the US with the feature disabled. Enabling the feature involved putting the unit into service mode and setting the country to Asia, then removing some plastic inserts, finally a cd/dvd holder had to be bought or you could modify an Epson holder (which is what I did). Its been great, and now Canon has new software that should work with this printer, the software was released along with the 4920.
I'm sure the 4920 will serve you well, hopefully it won't guzzle ink. Instead of getting compatible ink carts for mine I opted to refill the current ones with a refill kit (syringe and bottle of ink) can be messy if not careful though (I use gloves). I haven't had the need for a CIS system but have considered them in the past.