I have a pulsing xenia and it grows like crazy. I find it easy to keep.
I have read that low iodine will cause it to crash, and I have also read that it crashes in nature seasonally. It may come back after a crash too if you don't remove all the dead material. Wish I could be more specific on all this but I don't have the sources by me right now.
If you can find a cheap frag it is probably worth trying. I grew my first xenia in a nanocube deluxe (48w over 12gal) and it did just fine. It seems to have a richer, darker color now in my 75 gal. Maybe due to more light. Grows taller in that tank too. But either way it grows rather quickly, like a weed.
Can't believe some lfs charge so much for it sometimes. As easy as it seems to be for me, I would think it would be cheap. I have seen some lfs asking $75-125 for "show" xenia. Just seems ridiculous. Try finding someone near you who is giving away frags. Anyone near me is welcome to some of my frags. Just give me a small piece of lr and you can come take it from me. Sorry but I don't think I can ship it anywhere, it would probably take me forever to get around to doing it and I don't want to let anyone down.