I would only finish Ipe with an oil finish tailored to the wood. However, you must know that they will have to be refinished every year or less or they will turn grey. Film finishes won't stand the test of time and the environment and when they break down you have a mess to deal with that usually involves sanding back to a good finish.
Is a short article about finishing Ipe. I use an Ipe oil that I believe is from Messmers that has some UV inhibitors in it. I seem to remember that quite a few guys on here use Ipe for deck work and have much more experience than I do finishing it.
