I had it en masse several years ago. When i got it, the story behind it was that it would explode in growth, then die off, then explode, etc., repeating the cycle. Eventually most people ended up losing it. I experienced the same. I had it for about three years through the cycle and still have a tiny piece of it that happened to make it after the rest died off. It has better coloration than any other xeniid I've ever owned. I'm hoping the tiny piece I have sticks it out and pulls through for me.
When I had it in a very dirty tank (nearly no filtration and only a max of 10 pounds of LR-40 breeder with a 50 gallon livestock feed tub) under a 175W 14k coralvue bulb (not much light at all), it flourished and went from one stalk to probably 50 or 60. I consolidated that system into my main system, partially to gain some floor space back in the sunroom, but also to simplify my maintenance (multiple system can be a PITA). After consolidation, i had it in a relatively shallow system with T5 lighting. I am an SPS nut (but can't pass up any coral I don't already have, so the system itself is very mixed, just in different tanks sharing the same water), so I'd say the water was a bit cleaner (though I'm a lazy reefer, so it still isn't any where as clean as many SPS nuts' waterI balance needed maintenance with the color and growth of my Acros-if all is good or good enough for me, I do nothing additional

). It continued to do well and flourish for about the first year after transfer, then started to decline. I didn't see a mass die off, but every couple of weeks, I notice less and less of it.
It is an awesome coral. One of the few that looked better under sunlight than just about any I've owned. Showing it off under T5's, I often had to break out a flashlight to show how the sclerites glow and how the crown is a nice golden color. It seemed to have no issue with my other Xenia (mostly pulsing). Possibly jusy coincidentally, as my other Xenia began to increase in numbers, the electric blue cespit seemed to diminish. Strictly anecdotal, but it could be that the regular pulsing Xenia took the nutrient that had been available for the blue cespit. Of course, little happens in our tanks that can be linked to one cause, so if this was the case, I'm sure there was something else going on that aided in its decline and the growth of the pulsing Xenia.