Well i dont want to reach lvl cap, except if is so planned so precisely that u cant reach it until u do everything (kill everything and do every quest for max xp) in the world, because if it not planned good it kills exploration and what is not necessary to end the story since everything that u could do after reaching lvl cap becomes more or less pointless. For example this happened to me in Fallout 3 when i reached lvl cap halfway through the main quest since i was just exploring the wastelands killing everything i could, do many various sidequests, and when i reached lvl cap game more or less became just another FPS.
Now to solve xp distribution for companions and henchmen there could be simple Baldurs Gate like system where companions have different lvls depending on your lvl when u meet them.
