Hobbs heirloom 80/20 is a good choice, there are different 'lofts' available you can get a really thin one (i think it's the 'select' but not sure)but it was just perfect for my son who lives in Florida. I would not use flannel if he does not like the feel of flannel. and flannel does make them heavier than using the hobbs batting. i have had to deal with these problems myself, all 3 of the guys in my family; 2-son's & nephew moved to warm climates but they still love quilts...they just don't want them hot! the hobbs has been the best choice i have found.