You can keep xenia from spreading everywhere by only having it on a rock that limits its growth.  For the longest time, I had only one stalk and it had grown to the diameter of the piece of rubble it was attached to (slightly smaller than a golf ball).  Since the stalk wasn't able to spread anymore, it started growing branches like crazy.  I decided to move it to a larger rock, but first fragged off all of the branches onto small pieces of rubble.  Every couple of weeks, I can take in a couple of frags or re-frag them onto other pieces of rubble.  Yes, it does grow quickly if it likes your tank, but it is rather easy to control.  Limit its space (and anything the stalk can touch), and you'll limit its growth.
If you want highly desired, neon green polyped leather.  I certainly wish I had one.
I'd avoid yellow leathers, unless you can find one that looks healthy, which I have not been able to do locally.  They can be touchy.