I guess next to the difficulty of identification, experiences are also very different. This might be in water parameters, flow, substrate, hardware, fertilization contents and what ever mysteries there are more about mosses. F.e in the link Darrel points us to someone states Fissendens doesnt attach easy and grows slowly. In my tank Fissidens grows like crazy i find pieces all over the tank and attaches readily to anything i put it on as long as the texture is ok. F.e. in my case i have no problems with growing it to Mopani, to slate and clay based substrate in my case colombo and akadama. Not yet found it attached to river pebble. My alledged christmas moss, which probalby isn't even attaches to riverpebble but is not realy fond of growing emersed in it's aquatic form.
If i read about mosses and where the bryophite researchers report finding certain kinds, it is assumed some are prefering base and others acid invironments. So this most commonly means also even if it's rare to find in some environments, but still it can grow at other places as well, maybe less abundant but still does.
I come to guess that it's very important where the moss you get originates from, in what inveronment is it propagated. F.e. if you buy a moss which is propagated in a rather base environment or propagated on a base underground. Than you want to attach this moss to an acidic piece of redmoor wood it certainly will have trouble to do that. Maybe the ones who are having mopani instead which is found in the dry african plains and contains far less humic acids the moss would more readily attatch.
This is not just a theory
i'm already experimenting a while with all kinds of mosses.. and i've managed to grow mosses i've found under a tree growing on sand also grow submersed. But before it did i saw it go into a transition, first shrink away looking faul and dead for some weeks and slowly come back in a different form where it is hard to see its resemblance with the form it first had. i see the same happen to moss in aquatic form like stringy moss, growing up against hard ware from submersed to emersed and the emersed piece goes brown after 2 weeks looking dead, but i believe it isn't. its just drying out and going into a transition from sub to emersed.
With all this and reading others thoughts and findings and sharing mine in topics like this i come to find out that i (we) have to be very carefull with making statements about moss and how it grows. Maybe even about how some mosses should look or feel.
Moss is a rather mysterious and versatile, lovely and wonderfull little life form.