That flying movement is over the top. I don't remember offhand anything that moves that fast. So even young Korlocks are going to find survival best suited to running away. This level of speed in nature more closely correllates to fast herbivores like deer than ambushers like the great cats...
EDIT: Just noticed the ECL mod mention. I'd still dial them back to 50-60 ft at most, extend vision, and increase the skill bonuses. Look at the Dire Bat. At that point, I think they would be ECL +1/1.5.
I'd dial back that speed to 30 or 40, particularly given some of my assumptions to follow. Also, given that they are flyers, any work they do at night will make that blindsight of very limited usefulness. I suggest increasing it to 60, or even 90.
Just dropped by to maybe add more notes to my post on the Tarchons and had some inspiration for these new guys. Take it or leave it.
Communities: The Korlocks live in deep caverns usually accessed near the tops of mountains. The caverns are usually carved out as a few very large chambers with short, open-topped living quarters, the better to fly throughout their communities, as walking is something uncomfortable to this bat-like people, who instinctively recognize the danger of moving on the ground.
Wealthier communities make contacts with such creatures as Deep Dwarves, creating trade routes that such creatures can use to visit the Korlocks (or be visited by them) to trade those objects of wealth that the Korlocks choose to disgard. Since Korlocks prefer to be one with the night, they tend to lack appreciation for many forms of jewels and precious metals- these things do nothing more than attract attention, and are better traded for more practical equipment.
Games: The Korlocks like games of chicken. Two Korlocks fly around like the batty folk they are. This is done near the ceiling of the Korlock caverns, where what little light is kept by the community barely reaches. They then proceed to fly in tight circles, playing tag. Tag is best done by slamming another fellow into the wall. While only 'played' by youths, this harsh recreation is very effective at developing the battle and formation instincts of the Korlock warriors, who become skilled at sensing danger and being aware of other members of their team.
(Until puberty is over the information gained through blindsight is such an overpowering wash of information that they cannot use that sense without 'blindness' and headaches. Thus the communities do have some light, and games in the darkness help acclimate them to what so much of the rest of their lives will be.
Society: Korlock society is based not about providing for the community, but about roles in the hunt. The warriors are the main-stream fighters, very respectable and the reasonable goal for all healthy and strong young adults.
The next caste down is the scouts, who identify dangers and places to target. That they are less in caste is somewhat surprising, as these are often the most cunning members of society, with great authority in their direct connections to the highest caste warriors.
Lowest in society are the Gatherers, those who fly in while the warriors do battle to take what food or treasure they care to carry away. Young ones old enough to participate often enter combat as a Gatherer, even if destined for higher caste...
Combat: The Korlocks also prefer to fight melee-style, having enough of the primal hunter to appreciate the feel of tearing flesh. The main weapons of the gatherers are clubs and nets, and the Warriors typically use clawed gauntlets, blowguns, or hand-axes.