I hate to say it, but I think it is the only answer - it depends. I know that is sucky, but to be honest, that is the answer of lots of usb things on many linux distros as well. Things that should work don't, things that you figure will be a struggle start without any issues.
It is unsatisfying, I know - but I think that is realistic. Best thing would be for us to start a new post of things that DO work.
Again, though - to me, I'd rather dump something on my computer and stream it to the Roku, but that is because I have a computer on 24/7 and it is no biggie for me in my setup.
Those of you with 1-2tb of stuff, you would do better that way anyway if you ask me - you can setup nice sheets or xml files, or whatever, and share the fun easier. Of course, that may not work in your situation, but I'd recommend it.