OK, iso movement is also a problem since not everybody is going to want the same way to move. There's Diablo style, or grid, etc.
Not sure how 8 direction translates into iso, unless you just mean 8 direction with iso z ordering, which is almost the same as Diablo.
Which brings up another issue with z order, as we don't have an "official" way, and the usual way can be cpu intensive, but manageable.