No. The SD card slot only adds to the memory used for storing installed channels. This allows it to have more frequently used channels in memory and allow faster access to them without having to wait for the whole channel file to be downloaded again. And unless things have changed recently, no matter how big a card you put in, it will only use 2 GB.
SD card corruption is common, usually resulting in the Roku not going beyond the "bouncing letter" phase of the startup. Removing the card and reformatting it in a computer is the normal fix.
On recent Roku models, they just increased the amount of built in memory and did away with SD card support.
Rokus with SD card slots have always been picky re what cards they can use - all I can tell you is try it and see.
