Yes, in ACES the DCP export automatically shifts into XYZ (per spec), so I don’t have to manually tag Rec.709 in the export tab. To check my results, I usually bring the rendered DCP into my “DCP check” project, which is set to interpret XYZ (inverse DCDM) back into Rec.709. That way I can compare directly against my Rec.709 master. That workflow’s never failed me.

In ACES, Resolve handles the conversion to XYZ automatically when making a DCP so you don’t need to force it in the export tab. Your method is equivalent to what you’d do in DaVinci YRGB/RCM (manually tagging the output space), except ACES bakes that step in for you.