CHDs are typically just one file so its not like a MAME rom with multiple parts that are subject to change. I have seen them add new CHDs for a game and then they change one of the older CHDs name to have a o (old) at the end. They do add new games though usually just a few and sometimes not even every month. Most likely what you have would be fine as is but if you want to be completely up to date then my above suggestion still stands.