I don't know moonlight and don't know what you mean by “certain typed documents”, but AFAIK, OSMC is just Raspbian with some additional stuff. What I am saying is that media playback works just fine performance-wise for some media formats.
Moonlight is for game streaming. Basically if you want to run anything newer than an N64 on a Pi, you can stream it with moonlight from a more powerful computer. It's easy on local network, but can take a little bit more know how to set up for remote play (looked like if you want to play something on your phone away from home for example).