I have been keeping S. Haddonis for 12+ years now (( that is the age of my oldest one )), and I currently have 3 of them (( at one point did have 5 )). Over that time I have lost a total of 4 fish to them, 2 of which were a Mandarin and a Yellow Watchman goby -- two horrible fish to have in the same tank as an S. Haddoni. Overall, I would consider myself very luck to have only lost 4 fish, usually it would be a lot more.
IMO/E, the are 2 riskiest times for fish with an S. Haddoni -- first introduction -- could very well be chased, and could run right into the anemone; I've seen it happen. Second, would be an aggressive pair of spawning clowns with an S. Haddoni -- they will attack an existing fish, existing fish will chase the clowns, clowns go into Haddoni, existing fish is lunch.
In the end there are going to be risk, it is up to you if you want to take them.