The main malfunctioned and you cut it away? In my book, that qualifies as an emergency, and I wouldn't even think about it - the reserve would be out as soon as I could pull the handle. Personally, deploying the reserve is part of my emergency procedures. I would execute the EPs exactly the way I have practiced them so many times. Once I'm under a functioning canopy, then I would assess where I wanted to land. Yah, it sucks to lose a canopy, but there are worse things that can happen to you if you don't pull your reserve in time...