If you're looking for more design functionality in the cutting program, GoSign is definitely not the right solution. Like most free cutting programs, it's very basic, and really just designed to import a cut file and send it to the Summa cutter(similar to the previous Summa cutting software called Winplot).
Something like FlexiSign, which has more design functionality and the ability to also send cut files to the Summa, could be a better option for you. The Flexi Complete option has nesting built in, you can easily apply cut paths, and it also has functionality built in to facilitate printing and cutting(contour cutting) if/when you add a printer in the future. The downside of Flexi based on your original post is that is subscription or timed licenses(1-5 years) and it also they have not yet released an official Summa S3 driver, but everything else matches what it sounds like you're looking for(more design functionality, nesting capability, etc.).
Sadly, most of the software for design and cutting has moved to a subscription model and there are very few that actually let you purchase a full license. Aside from FlexiSign, you might also consider something like CoCut, but I don't think CoCut has added the S3 driver yet, either, and it's not as robust from a design editing and nesting standpoint compared to Flexi. I would expect most of these different cutting programs to have S3 drivers integrated by the end of the year, but it could potentially take longer than that to get them added.
Let me know if you have any other questions or if there is anything else that I can do to help.
Best regards,
Phil Johnson
Airmark Corporation
(800)527-7778, ext. 112
philj@airmark.com