dream orient is a very nice batting- has some nice loft to it, is silky soft to work with. as far as being cool in the summer- I don't know- with it being bamboo & silk...the quilt I used it in has flannel so it's warm all the time- can't judge that- my 'summer' quilt has Dream Wool batting in it! it is my all time favorite batting! the wool is totally washable- does not shrink- is lightweight, lofty, breaths- warm in the winter- cool in the summer- Fabulous!
you might want to visit the Dream Batting Company and read about the Dream Orient to find out it's breathability/insulating properties to find out.