Well Ive been cooking for some 40 years and have used drinking choc on many occassions, you do need to a just up the quantity DC and ajust down sugar and you will not get such a dark rich flavour it is slightly richer than using Milo, you can also if you want to go lighter still us Bournvita or ovaltine in cakeS, choclate ice topping can also be used.
Drinking choc makes a great creamy choc sauce too.