Very common combo.. Just make sure you have a way to get food down to your rays without your Dats eating it all, or overfeeding them. Keep in mind, rays and dats have alot of bioload.
no problelm i have it and otherd i know never a problem with that combo the only time i seen agresion was with a ngt he would try to push the rays out of his area
even big rays with small tigers/dats will work the rays may jump on them for a few days but them they will feel the sharp dorsal fin and then leave them alone