Even on teak I never liked to leave end grain open. Therefore, lockers ended up with a trim board all around, etc.

I've used Iroko, Ipe, Khaya (purports to be an African Mahogany though it can't hold a candle to Honduras Mahogany (angelic sounds of reverence playing in the background). Ipe will have small splinters, as will Khaya, though well sanded it works fine. The only Ipe we've gotten around here is in the form of ready cut/sanded decking material for house decks. About 1X4X3/4 radiused tops and square bottoms, so to speak. It's extremely dense. It's all glued fairly well for me but Ipe is hard on tools. If you're cutting a lot, watch for it starting to drag or burn in the cuts and change out the blade.

I've also used Purple Heart and left it outside untreated with success, too. But of course, Purple Heart is so interesting varnished it's a shame to just let it go gray.

When I did my teak veneer deck (1/8") on Passage, I bought 180 bucks worth of teak (1983 prices) with horizontal grain in an 8/4 dimension, ripped it so's it was all vertical grain in the veneer. Ended up with a 90 dollar stack of teak veneer and a 90 dollar barrel of teak sawdust.....