Yes, I last tried Cacti about a year ago though so I don't know what it's like now. I found Cacti rather fiddly to setup and use. I now use PNP quite happily as it's a doddle to get it working with Nagios.
Cacti is more of a full-featured application. If access control is important to you, I think Cacti would win as you can give different views to different users.
I'd encourage you to try both as they're both excellent in their own way. You could even get PNP to generate all the RRDs for you, and just use Cacti as a display engine.