I play with 8 different heroes and I've found that I seem to always have too much stone, even when I barely upgrade to level 3. Most buildings require food and lumber, but not so much stone.
Is there any thought to changing the balance on that?
That's because you play peacefully. Army requires a lot of stone. Plus excessive stone can be spend to speedup research via Petroglyph, but since this version has only Stone Age, there is no point for extra research.