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.
