The delta was designed before computer radios, the elevator and aileron setup was to allow you to have enough elevator throw without having too much aileron. Deltas are soft on the elevator and fast on the ailerons normally. The tapered tips of the aileron would be a anti-flutter tweak to the design.

Where you have the servo is good, nice direct stiff linkages. I'd glass the elverons, they can not be too stiff. I would also put a 1/2" tip on the wing so the elveron doesn't go right to the tip, it would do two things:
First it protects the elveron from being knocked during transporting.
Second it makes the tip vortex leave the tip, which is fixed and not going to flutter, rather than the end of the elveron which might flutter. I don't think you would have to taper the elveron if you put a tip on the wing.