Hi,
The actual limitation is that SRM does not support having one VM being replicated by both array-based replication and vSphere replication. If you wonder why, imagine a DR scenario where someone runs both plans (VR and array-based). You may end up with 2 different copies of that VM on your DR site.
In terms of recommendations you can do this:
1. Configure vSphere-replication for all VMs on a given replicated datastore. Do not add these VMs to a VR Protection group yet.
2. Confirm that replication is configured and add data is synced to the DR site
3. Delete the array-based protection group for that datastore and create a new VR-based PG for the VMs you selected at step one
4. Create a recovery plan
5. Run test
6. Once test is successful you can stop array-based replication.
By this approach you minimize your risks during cutover at the cost of increased bandwidth consumption while the same VMs are replicated by both array and VR. Even in the case of a DR event before Step 6, you still have a array-based replica of your data. It cannot be used by SRM, but you can recovery it manually.