well, i've had 5 of them for 1 year 4 months. I bought them before i realized they were hard to keep. I use tap water in that tank instead of ro/di. that's the only thing i do different that most, and have no clue if that makes any difference.
I've heard that the large Hawaiian feather dusters aren't very long lived. I've got several of the white and red feather duster cluster type in the back of my LR that are going on 19 months now. I try to remove as many as I can, but I can't reach those in the back. They're just too efficient at filtering phyto, that I don't want to have to compensate by adding more just so the critters and corals could get some.
I'm working on a year with my hawaiian.... but I feed a really mixed size food as well as occassional phytoplankton. I have also noticed that it likes to come out right after I scrape the front and there's lots of algae in the water column.