If anything 'nicks' the ends, they'll chip or possibly 'crush' the drywall. It's very soft as you know there isn't anything 'holding' the cured gypsum in place on the 'edges'. That is, IF your edges aren't the edges that come from the factory. (In other words, they're edges you cut ...)
Spend the $1.50 and buy the corner bead. You'll be glad you did. My best to ya and hope this helps.
Jay J -Moderator
PS: Hopefully, I understand that you're not simply cutting a hole in a wall where you're NOT cutting any studs. IF you're cutting studs, you still want to cripple out the hole and add corner bead.