I suspect 2GB might be small for some people.
Note that the 360 lets you store fonts and dicts on the SD card.
Me, I tend to go with the biggest fastest cards I can afford at the time because I expect the cards to outlive whatever hardware I buy them for. When I got my 360, I picked up an 8. (It's now running a 16GB I got for my media player; I wasn't using the extra space.) When I got the IQ, I went with a 32GB class 10. (It helped that it was on sale for $40.
)
Of course, the Plus does have WiFi and a browser so it might be able to access a personal cloud for storage, rendering the whole card question moot. 0 GB might be enough.