freedom 25 spinnaker/backstays

I have a round mast on my 1982 Freedom 25. The spinnaker is masthead rigged. Does anybody have experience/advice regarding the need for backstays. I know that the wingmast had a masthead spinnaker (with backstays)and that most round mast had a fractional rig spinnaker(without backstays). Am I at risk to damage/break my mast if I run without backstays in heavy winds??
Thanks,
Joe