Hi. New to the site but have been SW member since Mid 2011 and have lost just over 3st so far. Since the new book was issued at the beginning of the year there has been a slight increase in the amount of many HEXB cereals allowed. An example of this is Nestle Shreddies - previously 28g was allowed but this is now 30g. Hope this helps.
And no not all cereals are 30g, some are still 28g, some are 35g. Weetabix oatibix is 30g with no ryvita, so i think you could if you wanted to, but you don't get much, its about 12 pieces.