I've finally finished dwarven castes, so a new release will be today soon.
On regular basis dwarves learn skills at 50% rate now (combat skills at 125-150% rate because the mod is dangerous), however castes have bonuses to appropriate skills to fight it. Profession specialization by caste will be important, and there won't be as many legendary dwarves in your fort.
* 'Stone clan' dwarves are the most frequent caste of the mountain dwellers. They have thick skin and muscles and they almost lack pain receptors in these tissues. Also their bones are hard and heal quickly, so the frequent cave ins they cause are not a big deal for them. They are usually proficient miners, architects, engravers, jewelers and stoneworkers.
* 'Jade clan' dwarves often take roles of nobles and scholars because of their natural disposition to noble arts and medical skills. They become great doctors and accountants, however drafting them in army is a mistake.
* 'Clay clan' dwarves are known for their crafty hands, hospitality and friendliness. They love to work, to tend to plants and to cook. They become good crafters and farmers.
* 'Steel clan' dwarves are a rare caste, they are usually strong and agile and master combat arts quickly. They are immune to most diseases and ailments, and even some wizards cannot do anything to these stubborn dwarves.
* 'Shroom clan' dwarves are lazy bastards who will unlikely become important no matter what they do. They learn skills slowly, however they are cheerful idiots who can stay happy in most situations. They are usually used as haulers because they don't complain about heavy cargo or wet tunnels.
* 'Obsidian clan' dwarves are natural smiths and furnace operators. They learn these professions quickly and soon become legendary weaponsmiths and furnacers if assigned to the task.
* 'Dark clan' dwarves are touched by the corruption. They don't grow beards and have four tentacles on their face instead. They are often shun by other castes, but they tend to find a way with beasts and animals, thus becoming good animal trainers and trappers.
* 'Deep clan' dwarves are as sturdy as stone dwarves and prefer to live deep underground. They lack stone dwarves proficiency in stonecrafting, however they become great miners and furnace operators. While they can still get ill, they learned to resist most forgotten beast syndromes.
If you think that there definitely should be another caste which I missed, please suggest.