There currently isn't a way to see upvotes and downvotes separately in Sync like there is in some apps like Jerboa (I was wondering the same thing a few days ago), but it's listed as an enhancement request on Sync's GitHub so hopefully it'll be added at some point!
I hope downvote percentage can be added too, either displayed alongside the downvote number or a toggle between the two metrics—I missed the percentages from S4R.
Sync used to have it yeah, but he's overhauled the interface since they took it away so he'll likely need to design a new way to show it in the modern interface.
Either that or "controversial" worked back into Sync's algorithms. This feature and the missing "sync" function are deal breakers for me, as much as I love this app.