I have been thinking about this while I have been cycling to the office and back this week. At present I use a hybrid of the two versions and those that will get to play in my pbp game will be under these rules. I like the idea of group experience because it keeps the supporting characters advancing at the same or similar rates as the group super stars but on the other hand personal experience can favour the players that put the most effort into game.
I can see the logic that the whole adventure is a shared experience and the result of team work. The player is not necessarily playing every minute of every day yet the characters live those minutes. You play out the combats but not the hours of practice around the camp fire. As such the sparring partner could have just as much input into the final played out battle as the fighter wielding the sword but is never featured in the game.
I have seen two group experience methods. The first you just keep a tally of all the experience earned by the party and then divide that by the number of characters. Everyone earns the same. You can then of course add a bonus here or there for good play, ideas and such.
The other option is that you don’t bother keeping a tally of the experience earned. You just have a total award for completing the adventure. Once the adventure is over the party earns that amount of experience, again with or without bonuses for good play.
The pros are that the party all stay at roughly the same level and that characters such as the party healer do not fall behind the fighters because they cannot rack up the experience.
The cons are that some players may feel they are contributing a lot more than others to the success of the party but are not rewarded for that effort.
Here you are keeping a personal tally of all the experience earned for each character in the group and that is what they earn. Logically this is rock solid. The character used these skills and learned this much from doing so. The problem is that although the party wouldhave been nothing than a smear on the floor if it wasn’t for the healer, healing wounds does not attract the same experience as delivering them.
The pros are that effort is rewarded, the more you do the more you earn.
The cons are that it is easy for non combative characters to fal behind and that some characters can advance much faster than others creating an imbalanced party. When that imbalance equates to whole levels then the higher level characters find it easier to earn experience because they are stronger, tougher and more skilled than their colleagues and so they continue to earn proportionally more experience in a vicious circle.
I have adopted the experience system from RMU into my RMC game. RMU uses individual experience awards for defeating creatures and such (100-500exp) but also story awards (upto about 1000exp) for completing certain key elements of the story and finally plot awards that can be up to 10,000exp for completing major plot milestones. I am using the story and plot awards as party experience but with individual awards on top. I also do not see defeating a creature as having to kill the creature. If there are guards between you and your objective then killing the guards is only one option, sneaking successfully past them would be just as valid and, in my game, earn the same experience.
Each game session may contain several story milestones. In the last session I ran defeating the drow priestess was an important milestone as was the disposing of the drow magician and rescuing the dwarven slaves. The party sucessfully did all of these but only the priestess died (actually a lot of Drow warriors died but the party caught them by surprise during a religious vigil and it turned into a masacre), the drow wizard was forced to flee sacrificing his apprentice along the way and all the dwarves got out alive with their few possessions recovered from the Drow coffers. So in this case the party picked up three story awards.
So here we get a mix of the two with the largest awards going to the entire party but with individual awards to top them up.