Pipe cutter for me but tempted by that Superstar tool for the job, as others said the slight ridge files off in seconds with a metal file and to honest the one steerer I did with a hacksaw needed filing afterwards also so no big hassle.
I use Nukeproof headsets which come with a split crown race and can be pushed on by hand, no crown race setting tool required.
Star nut is a doddle to set with a screwdriver….insert stem of screwdriver through star nut, place star nut onto/over steerer with the metal length of screwdriver pointing into steerer, hit handle end of screwdriver with hammer/rubber mallet etc, star nut will gently move into and then down the steerer, keep hitting until at desired depth….the flat surface of the bottom of the screwdriver handle ensures the nut goes in flat and doesn’t end up sat skewed in the steerer.