I, like David, have had experience with these bugs for about 2 years.
I've treated with Seachem Reef Dip and have definitely seen the bugs fall off and die. I dip at about 3-4x the recommended dosage for about 15 minutes. I've never lost a coral due to this (most don't even slime) and at the end of the dip, any and all things crustacean are dead at the bottom of the container. Some bugs may retreat to the safety of the corallite, as I've seen one or two back on the coral at a later date, but I've not had them reinfest any corals that underwent the intense dip.
I have eradicated plague proportions of red bugs from several corals using this method. It doesn't always completely eradicate them from the piece (often it does), but it's the most successful "treatment" I've found. It may also help to have a powerhead in the dip container...I do.
As mentioned, water flow is a likely factor in their ability to infest I've found. Overall, IME, I've noticed the bugs will take hold after some sort of stressful incident - higher than average temperature for a couple days, low salinity among others. If the coral cannot resist them, it succumbs IME. If it is stressed (new, acclimating, slightly bleached or irritated) they take hold much easier. That's my experience with them anyway.
Many folks selling over the internet have them on their colonies and they look fine. I know quite a few reefers who have them on their corals and the pieces look healthy as ever. These are people who once battled them as well. A combo of the dip and more flow is what has made the change for the better in most of the cases.
From now on, I don't add any piece to my tank without a mega dip first...
