I'v had my FFCP for about a year now and have been considering S3D for about 6 months, the price is what was keeping me away. I use Slic3r on a iMac mostly, but also tried Cura and a couple of others along the way. I have always had issues with clogged nozzles, warping and bed adhesion. Three days ago I pulled the trigger and purchased S3D. My printer has been running 20 hours a day since and no problems at all.
Not saying S3D solved all the issues I was having but with all the controls and preset starting points it had established, they are now non-issues. Cosesidence? Good timing? Great product or a combination of the three? I only know that I am no longer cursing my machine daily because of failed/flawed prints.
My prints are near perfect now. And it slices faster than any other program I have used.
I am well satisfied with how it works and the interface is as good as Slic3r, maybe better now that I am getting used to it.
Everyone has an opinion and a preference. Share your's but don't shove it on anyone else.