Actually, a former incarnation of that tank from years back had java moss growing in it quite well. A little too well, it was a pain to keep trimmed in any attractive shape, and bits would get loose and sprout up all over the place. So it was removed, and we swore off mosses, but we were still weeding out those wayward bits right up until the day Stef rebuilt it.
The Christmas moss is our first attempt to try mosses again, and it seems a lot nicer in growth pattern, though I'm sure it's probably equally invasive. It's currently in an Eclipse tank, with both fluorescent tubes in the front. With the island attached high up on the back glass, it isn't getting full lighting, so it's growing slowly - but it is growing, and maybe in a month or two, we should have enough to incorporate it into Stef's tank.
As the person in charge of water parameters for all our tanks, I should also mention that I haven't gotten Stef's tank stable yet. First I added DIY CO2. Then the brand new check value clogged after a few days, leaving the tank without CO2, and the bottle blown up like a balloon! Now CO2 is only partially restored, because the diffuser isn't working right, and I'm waiting on a replacement. I can tell the plants are wondering what the heck is going on. Oh well, I'll get it straight eventually!