Welcome to the forum, Sam!
It's 0.82x, I'm afraid. I checked with Panasonic at the time to answer that same question.
Several people tried it and said it was optically good, but a bit bulky and heavy, so they tended not to carry it along.
I don't know where the .7x figure came from, except that as you say, it would make the attachment more salable.
I hadn't noticed Thorsten's mention that it was .7x. He's definitely the most knowledgeable person here in matters concerning the Digilux 2, as well as in producing excellent images with it. I guess this one got by him.