We were early adopters of the cDOT environment five or six years ago. In the early stages of deployment (five or six years ago), we saw some challenges around cDOT. However in the last two to four years, the product has matured incredibly. Ever since the introduction of ONTAP 9.X, we haven't seen any issues in terms of availability and performance.
We are upgrading to ONTAP, which will give us a data encryption level at an aggregate layer of the ONTAP environment. We are looking forward to that.
We are using SnapMirror and not seeing any issues. Let us hope it stays like that.