I'm personally of the opinion that if a device does what you want, then by definition it's not "outdated," no matter when it was released.
After checking the user's manual for the 6288, I do not see any information as to the size/addressability of the 4gb card, unfortunately. Rather than spending a lot of money on something that you might not be able to use, I'd consider 1) borrowing someone else's card to see if it can be used and/or 2) simply buying another 2gb card to use when your present card is full.