If I got the 200GB service and then backed up my 200GB of data, then had a disk failure... I would not be able to restore the data in the same month without exceeding the 250GB limits.
Just buy a 200+GB NAS system and put in in a friends house. And hope they have FIOS. You still have the 250GB limit, but save much money.
I think it is a great idea and I believe the story even mentions that the bandwidth used to do so will not count against you.
"Update: A Comcast spokesman in the comments below confirms that the service will count against your monthly cap" Quote from story at top of page. -- The weekend is here, grab a can of beer!