The stumpjumper fsr is a longer travel trail bike. One of the confusing aspects of Specialized's lineup is that the hardtail stumpjumpers are their race oriented hardtails, but their race oriented full suspension bikes are not the Stumpjumpers, but the Epics. I frequently scratch my head at that one.
The sugar, like the Epic, is very race oriented, which seems to be what you want. The stumpjumper FSR is perfectly raceable, but that's not it's main purpose. If you think racing will be a secondary priority and you also want to do some more "aggressive" fun riding, the stumpjumper would be a good choice.
Racing will be the main priority. But its good to get the confirmation that the Sugar is more similar to the Epic than the Stumpjumper. I felt pretty comfortable on that.