On Drum in Hat vs integrated into caliper - the drum in hat system has superior hill holding torque due to the wedging action and physical size of the shoes vs the small brake pads.
One other advantage to the drum in hat EB is that the calipers can be a fixed rather than floating calipers without having to use an additional mechanical caliper for the emergency brake. Not something I see anyone doing, but something I wanted to do someday and so it was a deciding factor for me.
I have had far more problems with calipers that have a built in e-brake setup than the drum in hat style. Just seems like I spend an inordinate amount of time trying to get the piston back into the caliper when I do a brake job. Pretty sure most shops don't even entertain the idea of using the existing calipers and always replace them when doing rear brakes on cars with calipers with the e-brake built in.
