In truth, I did get it working for a particular purpose but soon pulled it. For a few reasons, from memory, the main one was that there is no way to delete the uploaded files once no longer needed, so client-server space was quickly filling up. It was a while ago now, so I might be wrong on that bit.
There was also from memory an issue the upload process: IIRC when the user clicked “upload” the form jumped to next section, with no message that the upload had been successful. Or something like that. It was defo something that was creating me support requests from clients.
Again, raised it with Greg but can’t recall if it was fixed as I soon stopped using the stack feature after that. I’ve slowly pulled most instances of Formsplus from all sites now as the feedback I was getting from clients wasn’t positive. Nothing wrong with the stack but users just didn’t seem to like forms split over pages.
I also recall now my final issue with the stack: When the “next” button is clicked the form floats to the top of the page, and if you have a sticky menu it floats behind it. This to me just looked amateurish, so I requested having an option added to settings for an offset. I was bounced to another dev (who I think did the coding, Greg didn’t code, or summit like that) who offered it as a paid upgrade, so I mentioned it to another dev, who added it in about 5mins for free and even sent me a how-to video to put the feature back in after an update, and it worked well but after a few updates, I got fed-up having to edit the stack. Another reason I moved on.