First, congratulations on actually finding the Battat treehouse! I drove myself close to insane last holiday season looking for the thing!
I looked on ebay at the pictures - and honestly the Battat treehouse looks so much like the Maxim treehouse - I don't think it makes a bit of a difference which one you do have. As for quality - I am really not sure. From what I gather I think Maxim and Battat toys are pretty comparable. The Maxim does have add-ons however, if you think your dc will be really into it.
DD - 6 y.o.
DS - 4 y.o.
DS - 2 y.o.
DD - 8 months