Currently using S3D (4.0) with FLUX Delta+. Some minor issues but no big show stoppers.
I have not found a way to direct print from S3D to FLUX via USB or wireless, I don't believe it is possible yet.
Write out as SD card data (gcode) and import into FLUX Studio to print.
I used S3D to perform customized print support printing is fantastic.
The simulation of printing is great for checking if any likely to fail to print
however would need some experience of printing stuff to know.
S3D has a default FLUX DELTA FFF seems to work fine most of the time (90-95%)
S3D has so much features more to learn about them.
If you ask is it worth the USD$150? YES~!