We must avoid the generic levels based system at all costs. It\'s the lazy way to go.
Stats should evolve independently based on individual use.
As for the use it or lose it thing: I don\'t see any connection between opposing stats or skills. In fact, I don\'t see anything \"opposing\" with them at all. The onnly thing that might be a problem is STR vs. AGI, because it might be detrimental to agility if you\'re packed with muscles. However, I still don\'t think it will be noticable.
The magic skills are the big ones. Some of the various other skills have some \"opposites\" too, like offensive stats vs defensive stats, but the main ones wouldn\'t need much of this.
What we want is the character advancement to be determined by the style of the player. I agree, the time method has issues. It forces the player to be an addict to get the highest stats. I would say that a total dependence on time would be decremental to gameplay. (I might consider gameplay time instead of world time, but I don\'t know.) That\'s why I suggested the counter-balancing points thing. You\'d be gaining small amounts of experience in every skill you\'re using, at all times. The counterpoints would be used to neutralize the advancements other than your focus. Additionally, with the weapon skills we don\'t want everyone to be experts in all skills. We want to force characters to pick a role. This is most easily done by requiring skills to be maintained, one way or another.