Eh. I posted a few reasons why not to have an XP or leveling system.
I guess the bottom line is, this is what makes the game more unique than others. I'd rather see other things coded than a reward system for playing a lot.
If there are any rewards, they should be purely aesthetic or something. No giving any advanatages over someone else.
The way its set up right now, someone new can join and kill anyone they want, without going through training or leveling. Its just get up and go. Do whatever you want from the start.
I know that I probably wouldn't protect anyone. I've had enough with "escort missions". Its either I'm working with someone, or I'm not. No parasitic relationships, at least not until I start getting a large possitive flow of capital, most likely from the source I am protecting.
Also, new people already have an advantage over everyone for four hours. Thats way more than enough time to increase your playing skill to about the same as everyone else, and learn everything there is to know about the game.