Most of sugar is Gtk3 so it doesn't use hippo canvas.
Hippo canvas is used by gtk2 activities to do custom drawing. The only one that I think uses it is the wonderful turtle blocks activity.
It should be OK, but you won't have access to turtle blocks
I think @walter was going to do the gtk3 port due to other reasons, but this is an interesting addition to the list of reasons (hippo canvas got removed from arch).