Actually, we may not say, more powerfull then powermill, but there are certain issues.
1. I am doing my desinign expertly in Creo and Catia. Both are parametric and capable to machine.
2. In Creo, we can control most of our machining options. In Catia we can control with some limit. But in Powermill we cant (may be I need to learn more).
3. I like to work all in only one software. From part modeling to final CNC machine. Catia or Creo are best.