Good question. DxO Pro doesn't yet work directly as an Aperture plug-in - hopefully it will in a future release. There is a small program called Catapult you can download that will manage the transfer back & forth. It takes a little getting used to but it does work well and can be used with other programs that are not native plug-ins.
I'm really liking the control I have processing RAW files in DxO Pro. It comes on special fairly regularly and they are very diligent about keeping it updated.
Kelowna BC Canada