It's just the work setting up the surveys. Until now we only had to copy the old survey.
Set up the latest 3.x LTS in parallel, it doesn't cost you anything, at least not more than maybe 5-10 minutes to set the new installation up (mabye 15min if we include the upload).
Then you export one of your surveys as LSS and import it into the new installation. This should work without problems. Test it. if everything else is fine, export and import all of your surveys to the new system.
So no need to create the surveys from scratch. If you use some workarounds, they might not work with the newer version, but the same problem you would have with any upgrade either. And if you have custom templates/designs, they will need to be adapted to the new templating system. But here also the same when upgrading.
So if you don't have many users and only few base surveys that you would like to use again, then the setup of a new installation including copying the surveys might take you between 30-60min. I think it is the cleanest approach.
And from then on you just keep up with the updates and CU should work like a charm.