A couple of world rounds should see you OK for a good result.
Joking aside, I did my first this year and its not your standard level that matters as much as your ability to over come the thought at each section that you must survive 'til Saturday afternoon. It changed the way I approached the sections (for to worse)and I never managed to ride a single section like I would in a one day event. I'm an OK rider riding the hard route at club level but you wouldn't have known that from watching me or looking at the scores.
One thing I did learn though, unless you are a very good rider, approach it as a two year trial. 1st year learn the ropes and 2nd year have a real go.