It depends on the year model.  The older Rotax 4-TEC motors could use synthetic.  The supercharged motors could not because of the ceramic slip washers coming apart, causing damage from a lack of oil because oil ports would get stopped up.  The synthetic oil is too slippery for the clutched superchargers.
They have since stopped using that set up and using a steel washer.  I read an article last season that said they are now using mineral oil.  
I see you have an 08 model 215 hp.  I use synthetic oil in all my 90 model 787cc motors.  But, if I owned the newer, supercharged 4-TEC, I think I'd stay with regular mineral oil.