I'm currently running Versaworks with a BN-20, using Affinity designer for Mac and generally having no issues. I simply take my vector work, duplicate it, and expand stroke, then convert it to a spot color. If I need an offset, I make the stroke the width I need, expand it, and then remove the inner stroke lines, then repeat the aforementioned process. Cut contour works quite easily!
That being said, the one thing I haven't been able to find yet is any information on how to do a perf cut with Affinity. Roland offers swatch files for Illustrator and CorelDraw, but not affinity of course. I've tried to replicate those swatches in Affinity watching videos of people setting them up manually in Illustrator, but even setting up the same spot color it doesn't seem to work. I'm planning to try a trial of Illustrator (Adobe lost me as a customer when they switched to subscription based), install the swatches, and then export a PDF with the swatches laid out as samples and see if I can make that work in Affinity. Fingers crossed!