Java moss is a bit messy mate tbh. christmas moss or weeping moss is much better and alot tidier. If left, Java Moss will fill a tank of any size. It require trimming every so often which you would be able to sell/donate to other members.
Not necessarily slower, but is alot more uniform and neater. Java Moss grows looser too. A nice clump of Christmas moss wrapped around a branch and tied on with cotton wrapped around a few dozen times will look alot better and will stay 'close'
Added to a branch above the substrate it will weep down and you won't need to touch it for months... Takes a few weeks for it to get a hold onto the wood and may look a little unhealthy, but once it adjusts to your water conditions then it really starts to grow! It is the most expensive of the three, but when you come to trim it you can add it to something else in your tank.