Got to rasterize your gradients, better yet create them in Photoshop adding a touch of noise then save as Tiff uncompressed, import into Flexi and mask with desired elements, sounds like a lot of troublesome work but it's actually quick and easy. This is the key to successful prints from a Colorcamm, learning how to build your files for optimal output.
And yes Flexi pro is the most efficent software to run a Colorcamm, IMO.