AFAIK it's always been unlimited.
I think a "very large" cap would be acceptable (2tb is rather excessive... even tho I would "just" have space for that I'd be hard pushed to actually use the pc and would have to clear everything except the o/s to make room

).
I have absolutely no idea what would be considered "reasonable" by the "we don't have a cap" BY customers (myself included)... but once the door is opened to capping there never appears to be an acceptable level.
Personally I think I've d/l around 500gig over a 3-4 year period (not entirely sure but thinking of how much h/d space I have and how much is used, and I don't remember deleting much except the odd picture...) but that doesn't include up/downloading to my website (can't see that being huge cos it's still relatively new with mainly words rather than pictures)... don't have a clue how much I've uploaded tho