yeah sodium loading is a good idea...i havent done the cube i just add salt to all my meals...i like sea salt.
the thing to remember about sodium loading is that you need to get the timing right...what i have found that works the best is to start loading on sunday before the show and do it up through wed....by thurs. you should completely cut out all sodium...it will take your body a couple of days to normalize so for those few days you will lose alot of water...another important thing with sodium loading is to make sure that you are drinking alot of water...you should actually overdrink/waterload for about a week before you start the sodium load.