Although it does not apply to decking per se, it is good to know that Ipe is not a species of wood, rather a general class of hardwoods containing lapacho. Anyways, why this is relevant to woodworkers is that lapacho is a chemical that destroys glue bonds as it leeches to the surface of the wood, so any glue joint over time is pretty much guaranteed to fail. There have been lots of tests done with lots of different glues, some work well for days or weeks others fail to take at all. Here is a good discussion on the topic at
Woodweb
So just remember to use mechanical fasteners when working with Ipe, you just might want to skip the glue altogether and save yourself some time and money.