The 163's inner trailing edge 'elevators' were for trimming the pitch change caused by the under wing flaps. Deltas really don't need them (flaps), providing the balance is right and you can get the wing up to the large alphas deltas can use...the drag increase is huge and the speed can be really slow, flaps really wouldn't work with them...generally it means that if you are using a prop it needs to be at the front...
Evan.