That's an essential game mechanic, how do the players level up? Do they at all? I am interested in this system, if nothing else it seems like it would get rid of the motive of killing purely for XP. Why do *you* do it this way?
These days, all of my campaigns are run sans-XP.
Instead, the players level up at appropriate story points. Ferinstance, I "recently" ran a short campaign, starting at 1st-level, in the Great Dale in the Forgotten Realms.
It was a kind of murder-mystery-meets-geopolitics-meets-dwarven-tunnels kind of mash-up.
So, when the players found their way to the dwarven tunnels (which took a couple play sessions), they gained a level. When they figured out who had murdered a bunch of people (which took a couple more), they gained a level. Etc.
This works because, since I've been DMing and playing for years-and-years, I've got a decent handle on pacing, and have decided that I can achieve the results that an XP system tries to provide (e.g., meaningful, tracked progress towards incremental character power) by just shoe-horning in the results. I don't particularly need the intermediate step of calculating and assigning XPs.
EDIT: I don't think it would work for all groups or all campaigns, and certainly not for new DMs who are still learning the ropes.