It really depends on what you want from Superfly.
For me, I wanted better promo renders, more realism. But, I can't "afford" to take days for a single promo render when I have to do 6-10 of them.
Now, I have a Nvidia card in my computer, but it's not one of the new full of RAM cards and I don't use it for Superfly renders - it's just too slow. So I use CPU rendering.
Given those parameters, these are my render settings for most Superfly renders I do.
With these settings, I get a Superfly promo in about the same amount of time an IDL lighted SSS render takes in Firefly - around 30 minutes per render.
Keep in mind lighting is even more important in Superfly than in Firefly. If you are just starting with Superfly, I highly recommend you use Ghostship's free Superfly lights:
https://sharecg.com/v/86639/gallery/11/Poser/Studio-Portrait-Lights-for-Poser-11-Poser-11-Pro to get you started with Superfly.
Again, remember that this all works for a specific purpose. The beauty of Superfly is that you have the ability to change all of these parameters for your own purposes. The only expense for doing so, might be longer render times.