The only issue that occurred to me is dice rolling. The PbP stuff I normally do is on a site called RPoL.net and it has a dice roller built in.
Wizards has a dice roller:
http://www.wizards.com/dnd/dice/dice.htm
Can always use screenshots to verify the role. Or pick up copies of Fantasy Grounds which is a virtual table top. I used it for years before I managed to get myself 2 games to play and 1 to run.
Yes Play by post of D&D, but not FATAL. Like I said. FATAL breaks a lot of the forum rules by the rulebook alone. I could do a lot of different systems though. My favorite setting being SCION from white wolf.
But rules wise I can't compete with Pathfinder.
And like our lord and master Petra says. Fable may be good (It is) but I have yet to see a computer game even come close to comparing with a tabletop game. being tabletop games have almost unlimited freedom of actions.
Also never played Savage World. So it's pretty good? What's the setting like?
Savage Worlds is the system. It has 1 corebook for the whopping price of $9.99 and it's fairly small unlike other books. All your stats are based off dice (for example, my character has a d8 strength, d4 spirt, d6 vigor, etc) and there aren't many modifiers. Having a +2 in something is huge...
The other half of the game is the setting book. There are dozens upon dozens of settings now. My favorite is called Necessary Evil and it's usually ran as a very slap stick, marval super villain game.
Other settings are Suzerain, which is a time travel type game; deadlands, wierd wars, evernight (epic fantasy), shaintair (avoid), rippers (victorian age horro), low life (if nothing else, the drawings are awesome), 50 fathoms (pirates), and there's tons and tons more.
It's very rules light and prep is pretty easy as the DM.