Well... before I actually get back to work, since I've started detailing out these systems (albeit haphazardly), I might as well mention what I intend for the game in a more general sense.
I intend to create an incredibly immersive experience. One that feels like you and your own story the whole of the way. This is my response to the casual-hardcore issue--that there is in short no issue split between the two. The matter is actually refreshing simple: a game should be one that you enjoy anywhere. Argumentative issues of comparative advantage only arise when people are bored enough to consider it as more important than the game experience itself.
Would I add 'casual-friendly' concepts into the working of the game? No. Would things that could be considered 'casual-friend' exist in the game? Yes. But only because they are, for other reasons, common sense.
For me, this largely has to do with increasing depth as levels increase, rather than increasing primarily in stats. A high-level could certainly go back to a more finely limited depth to compete in some manner of swordsmanship challenges under fair (or no-magic) rules. His only advantage then would be his personal experience.
I'd like to be able enjoy being a town errand boy through the interactions with the townspeople and my employees as much as a guild craftsman assembling parts for a senior guildsman who teaches me bit-by-bit as I work for him, as much as a rookie gladiator (not refering to class) in Ul'duh, as much as an adventurer out on the field, as much as a specialist gather with whom craftsman contract for their rare goods, as much as a guild sub-commissioner arming and preparing a small militia force of mixed AI and players for missions in the area, as a member of a circle of friends training with each other and adventuring with each other and fighting by each other's side in the occasional meeting of sparring circles in La Noscea.
When we move past or previous settings, we shouldn't be doing so with a "good riddance" or because there's nothing more to be done there. Enjoy every moment, in a world with systems deep enough to learn from every moment.