This thought is prompted by seeing games (live plays as well as text descriptions) where revealing the internal details of characters, and even whole plots is common.
My feeling is that MU* RP is more about finding out in the moment, seeing something unexpected, a surprise, a creation in the next bit of text. I also recall folks who dislike MU* RP having such info in it.
So perhaps consider for 2-3 familiar players, MU* in general, and some for of table-top where the players are decently familiar with one another.
How important is it to you to be able to, or not have to, explain your character's thinking, emotions etc to a table of RPers?
How do you feel about others doing to when you are at the table?
How about the GM describing the NPCs actions?
On a similar vein, how interesting/important is it to you to be able to keep secrets from the other players - meaning whatever it is, it is never discussed in front of them until it's revealed in game fiction?
Same again for other players at the table?
Same again for the GM and their NPCs?
Someone I spoke to about this also brought up character betrayal. Everything from minor theft, to relatively small working at counter purposes, to full on setting characters up to take a hit.
I myself have never seen that on a MU* where it wasn't really a player using IC lies to cover for OOC lies.