I'm happy to believe that there are times when it can be useful -- but not for assessing likely August 2014 availability in August 2013.
Thanks for the responses.
I think the tool is good for checking where your Avios can take you, but not for checking availability for more than 1 person.
I was trying to avoid checking all the destinations one by one, I was hoping there was a method of showing all availability at a certain time in a certain class.