I doubt if there is any official guide which has parity difference between the two tools. However, the best advise would be to have a look at the features & advantages mentioned in the "SnapCenter plugin for Oracle" and see if there is anything that you are missing from your current product and even cross check with the features in SMO TR or docs.
For features please read slides from "26 to 30" of the attached pdf.
Also, this pdf covers the same in detail.
SnapCenter Plug-In for Oracle Database
https://www.netapp.com/us/media/tr-4700.pdf
Also, this section is useful when importing data fro SMO to SnapCenter.
http://docs.netapp.com/ocsc-41/index.jsp?topic=%2Fcom.netapp.doc.ocsc-isg%2FGUID-609283E1-DEE3-4BD0-A421-29DEC0BC9BBB.html
Most importantly : SnapCenter is the only way forward, nothing better than having all the different SnapManager Products bundled into one Management server with the same underline core NetApp's technology like - WAFL/snapshot/cloning/Mirroring/Vaulting etc.
Thanks!
