I would buy the Hornady. I have and use this one. The RCBS is just as good, but usually more expensive. I have several CH4D dies. Most work well. I have had burrs in one die that should not have been. I would not pass up the CH4D if it was significantly less expensive. They have always corrected any issue for me.
Welcome to the 9.3X57 fan club. I will look to pick mine up after finally having the scoping and swing safety put on. Maybe tomorrow. I have two, but the 1898 action rifle will eventually end up as a 9,3x62 as soon as I can find a smith to do the job.
Best wishes.