I've had my Powder Blue for almost a year now. I keep it with a Purple Tang and Clown Trigger. He has been a pleasure from the get-go. I haven't had any problems yet and I don't intend on having any because I'm not adding any more fish with these guys. As for hypo it can be a very good method at times, but definitely not sure fire for getting rid of ich. When I first got my Purple Tang it had ICH and I used hypo for 5-6 weeks and it never completely got rid of the ich. From some of the research I've done hypo is a debateable method. If I were you I would use very low dose copper treatment. You have to be careful because they (PBT's) have a bacteria in their stomach (something to do with digestion) and they can be harmed by copper. So there is definitely a trade-off.
I actually think Powder Blues aren't too difficult to keep. I had a Bi-Color Angel that was a lot harder to keep. My experience has led me to believe that each fish is different and unique in that it has it's own indivdual needs to be successful in the home aquarium. I think a lot of the research you'll find on Powder Blues, or any fish for that matter, is simply a general set of guidelines to help you get started in keeping a particular fish. Many of the things other people mentioned should help you in chosing your next powder blue if you so chose to get another. Hope this helps.